diff --git a/src/backend/core/tests/contacts/test_core_api_contacts_create.py b/src/backend/core/tests/contacts/test_core_api_contacts_create.py
new file mode 100644
index 0000000..1168a38
--- /dev/null
+++ b/src/backend/core/tests/contacts/test_core_api_contacts_create.py
@@ -0,0 +1,706 @@
+"""
+Test contacts API endpoints in People's core app.
+"""
+
+from django.test.utils import override_settings
+
+import pytest
+from rest_framework.test import APIClient
+
+from core import factories, models
+from core.api.client import serializers
+
+pytestmark = pytest.mark.django_db
+
+
+CONTACT_DATA = {
+    "emails": [
+        {"type": "Work", "value": "john.doe@work.com"},
+        {"type": "Home", "value": "john.doe@home.com"},
+    ],
+    "phones": [
+        {"type": "Work", "value": "(123) 456-7890"},
+        {"type": "Other", "value": "(987) 654-3210"},
+    ],
+    "addresses": [
+        {
+            "type": "Home",
+            "street": "123 Main St",
+            "city": "Cityville",
+            "state": "CA",
+            "zip": "12345",
+            "country": "USA",
+        }
+    ],
+    "links": [
+        {"type": "Blog", "value": "http://personalwebsite.com"},
+        {"type": "Website", "value": "http://workwebsite.com"},
+    ],
+    "customFields": {"custom_field_1": "value1", "custom_field_2": "value2"},
+    "organizations": [
+        {
+            "name": "ACME Corporation",
+            "department": "IT",
+            "jobTitle": "Software Engineer",
+        },
+        {
+            "name": "XYZ Ltd",
+            "department": "Marketing",
+            "jobTitle": "Marketing Specialist",
+        },
+    ],
+}
+
+
+def test_api_contacts_list_anonymous():
+    """Anonymous users should not be allowed to list contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().get("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_list_authenticated_no_query():
+    """
+    Authenticated users should be able to list contacts without applying a query.
+    Profile and overridden contacts should be excluded.
+    """
+    user = factories.UserFactory()
+    factories.ContactFactory(owner=user, user=user)
+
+    # Let's have 5 contacts in database:
+    assert user.profile_contact is not None  # Excluded because profile contact
+    base_contact = factories.BaseContactFactory()  # Excluded because overridden
+    factories.ContactFactory(
+        override=base_contact
+    )  # Excluded because belongs to other user
+    contact2 = factories.ContactFactory(
+        override=base_contact, owner=user, full_name="Bernard"
+    )  # Included
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/")
+
+    assert response.status_code == 200
+    assert response.json() == [
+        {
+            "id": str(contact2.id),
+            "override": str(base_contact.id),
+            "owner": str(contact2.owner.id),
+            "data": contact2.data,
+            "full_name": contact2.full_name,
+            "notes": "",
+            "short_name": contact2.short_name,
+        },
+    ]
+
+
+def test_api_contacts_list_authenticated_by_full_name():
+    """
+    Authenticated users should be able to search users with a case insensitive and
+    partial query on the full name.
+    """
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="David Bowman")
+    nicole = factories.BaseContactFactory(full_name="Nicole Foole")
+    frank = factories.BaseContactFactory(full_name="Frank Poole")
+    factories.BaseContactFactory(full_name="Heywood Floyd")
+
+    # Full query should work
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=David%20Bowman")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Partial query should work
+    response = client.get("/api/v1.0/contacts/?q=ank")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ole")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ool")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+
+def test_api_contacts_list_authenticated_uppercase_content():
+    """Upper case content should be found by lower case query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="EEE", short_name="AAA")
+
+    # Unaccented full name
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_capital_query():
+    """Upper case query should find lower case content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=EEE")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=AAA")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_content():
+    """Accented content should be found by unaccented query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="ééé", short_name="ààà")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_query():
+    """Accented query should find unaccented content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=ééé")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=ààà")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_retrieve_anonymous():
+    """Anonymous users should not be allowed to retrieve a user."""
+    client = APIClient()
+    contact = factories.ContactFactory()
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_retrieve_authenticated_owned():
+    """
+    Authenticated users should be allowed to retrieve a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": str(contact.owner.id),
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_public():
+    """
+    Authenticated users should be able to retrieve public contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": None,
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_other():
+    """
+    Authenticated users should not be allowed to retrieve another user's contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 403
+    assert response.json() == {
+        "detail": "You do not have permission to perform this action."
+    }
+
+
+def test_api_contacts_create_anonymous_forbidden():
+    """Anonymous users should not be able to create contacts via the API."""
+    response = APIClient().post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David",
+            "short_name": "Bowman",
+        },
+    )
+    assert response.status_code == 401
+    assert not models.Contact.objects.exists()
+
+
+def test_api_contacts_create_authenticated_missing_base():
+    """Authenticated user should be able to create contact without override."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": {},
+        },
+        format="json",
+    )
+    assert response.status_code == 201
+
+    new_contact = models.Contact.objects.get(owner=user)
+
+    assert response.json() == {
+        "override": None,
+        "data": {},
+        "full_name": "David Bowman",
+        "id": str(new_contact.pk),
+        "notes": "",
+        "owner": str(user.pk),
+        "short_name": "Dave",
+    }
+
+
+def test_api_contacts_create_authenticated_successful():
+    """Authenticated users should be able to create contacts."""
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Existing override for another user should not interfere
+    factories.ContactFactory(override=base_contact)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 3
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": str(base_contact.id),
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.override == base_contact
+    assert contact.owner == user
+
+
+@override_settings(ALLOW_API_USER_CREATE=True)
+def test_api_contacts_create_authenticated_existing_override():
+    """
+    Trying to create a contact overriding a contact that is already overridden by the user
+    should receive a 400 error.
+    """
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+    factories.ContactFactory(override=base_contact, owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "notes": "",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 400
+    assert models.Contact.objects.count() == 2
+
+    assert response.json() == {
+        "__all__": ["Contact with this Owner and Override already exists."]
+    }
+
+
+def test_api_contacts_create_authenticated_successful_with_notes():
+    """Authenticated users should be able to create contacts with notes."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+            "notes": "This is a note",
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 1
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "This is a note",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.owner == user
+    assert contact.notes == "This is a note"
+
+
+def test_api_contacts_update_anonymous():
+    """Anonymous users should not be allowed to update a contact."""
+    contact = factories.ContactFactory()
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+    response = APIClient().put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_update_authenticated_owned():
+    """
+    Authenticated users should be allowed to update their own contacts.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user)  # Owned by the logged-in user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_profile():
+    """
+    Authenticated users should be allowed to update their profile contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_other():
+    """
+    Authenticated users should not be allowed to update contacts owned by other users.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory()  # owned by another user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 403
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_delete_list_anonymous():
+    """Anonymous users should not be allowed to delete a list of contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_list_authenticated():
+    """Authenticated users should not be allowed to delete a list of contacts."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    factories.ContactFactory.create_batch(2)
+
+    response = client.delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 405
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_anonymous():
+    """Anonymous users should not be allowed to delete a contact."""
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    response = client.delete(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_public():
+    """
+    Authenticated users should not be allowed to delete a public contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.BaseContactFactory()
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_owner():
+    """
+    Authenticated users should be allowed to delete a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.count() == 0
+    assert models.Contact.objects.filter(id=contact.id).exists() is False
+
+
+def test_api_contacts_delete_authenticated_profile():
+    """
+    Authenticated users should be allowed to delete their profile contact.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.exists() is False
+
+
+def test_api_contacts_delete_authenticated_other():
+    """
+    Authenticated users should not be allowed to delete a contact they don't own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+ 
diff --git a/src/backend/core/tests/contacts/test_core_api_contacts_list.py b/src/backend/core/tests/contacts/test_core_api_contacts_list.py
new file mode 100644
index 0000000..1168a38
--- /dev/null
+++ b/src/backend/core/tests/contacts/test_core_api_contacts_list.py
@@ -0,0 +1,706 @@
+"""
+Test contacts API endpoints in People's core app.
+"""
+
+from django.test.utils import override_settings
+
+import pytest
+from rest_framework.test import APIClient
+
+from core import factories, models
+from core.api.client import serializers
+
+pytestmark = pytest.mark.django_db
+
+
+CONTACT_DATA = {
+    "emails": [
+        {"type": "Work", "value": "john.doe@work.com"},
+        {"type": "Home", "value": "john.doe@home.com"},
+    ],
+    "phones": [
+        {"type": "Work", "value": "(123) 456-7890"},
+        {"type": "Other", "value": "(987) 654-3210"},
+    ],
+    "addresses": [
+        {
+            "type": "Home",
+            "street": "123 Main St",
+            "city": "Cityville",
+            "state": "CA",
+            "zip": "12345",
+            "country": "USA",
+        }
+    ],
+    "links": [
+        {"type": "Blog", "value": "http://personalwebsite.com"},
+        {"type": "Website", "value": "http://workwebsite.com"},
+    ],
+    "customFields": {"custom_field_1": "value1", "custom_field_2": "value2"},
+    "organizations": [
+        {
+            "name": "ACME Corporation",
+            "department": "IT",
+            "jobTitle": "Software Engineer",
+        },
+        {
+            "name": "XYZ Ltd",
+            "department": "Marketing",
+            "jobTitle": "Marketing Specialist",
+        },
+    ],
+}
+
+
+def test_api_contacts_list_anonymous():
+    """Anonymous users should not be allowed to list contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().get("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_list_authenticated_no_query():
+    """
+    Authenticated users should be able to list contacts without applying a query.
+    Profile and overridden contacts should be excluded.
+    """
+    user = factories.UserFactory()
+    factories.ContactFactory(owner=user, user=user)
+
+    # Let's have 5 contacts in database:
+    assert user.profile_contact is not None  # Excluded because profile contact
+    base_contact = factories.BaseContactFactory()  # Excluded because overridden
+    factories.ContactFactory(
+        override=base_contact
+    )  # Excluded because belongs to other user
+    contact2 = factories.ContactFactory(
+        override=base_contact, owner=user, full_name="Bernard"
+    )  # Included
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/")
+
+    assert response.status_code == 200
+    assert response.json() == [
+        {
+            "id": str(contact2.id),
+            "override": str(base_contact.id),
+            "owner": str(contact2.owner.id),
+            "data": contact2.data,
+            "full_name": contact2.full_name,
+            "notes": "",
+            "short_name": contact2.short_name,
+        },
+    ]
+
+
+def test_api_contacts_list_authenticated_by_full_name():
+    """
+    Authenticated users should be able to search users with a case insensitive and
+    partial query on the full name.
+    """
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="David Bowman")
+    nicole = factories.BaseContactFactory(full_name="Nicole Foole")
+    frank = factories.BaseContactFactory(full_name="Frank Poole")
+    factories.BaseContactFactory(full_name="Heywood Floyd")
+
+    # Full query should work
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=David%20Bowman")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Partial query should work
+    response = client.get("/api/v1.0/contacts/?q=ank")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ole")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ool")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+
+def test_api_contacts_list_authenticated_uppercase_content():
+    """Upper case content should be found by lower case query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="EEE", short_name="AAA")
+
+    # Unaccented full name
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_capital_query():
+    """Upper case query should find lower case content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=EEE")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=AAA")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_content():
+    """Accented content should be found by unaccented query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="ééé", short_name="ààà")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_query():
+    """Accented query should find unaccented content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=ééé")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=ààà")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_retrieve_anonymous():
+    """Anonymous users should not be allowed to retrieve a user."""
+    client = APIClient()
+    contact = factories.ContactFactory()
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_retrieve_authenticated_owned():
+    """
+    Authenticated users should be allowed to retrieve a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": str(contact.owner.id),
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_public():
+    """
+    Authenticated users should be able to retrieve public contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": None,
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_other():
+    """
+    Authenticated users should not be allowed to retrieve another user's contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 403
+    assert response.json() == {
+        "detail": "You do not have permission to perform this action."
+    }
+
+
+def test_api_contacts_create_anonymous_forbidden():
+    """Anonymous users should not be able to create contacts via the API."""
+    response = APIClient().post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David",
+            "short_name": "Bowman",
+        },
+    )
+    assert response.status_code == 401
+    assert not models.Contact.objects.exists()
+
+
+def test_api_contacts_create_authenticated_missing_base():
+    """Authenticated user should be able to create contact without override."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": {},
+        },
+        format="json",
+    )
+    assert response.status_code == 201
+
+    new_contact = models.Contact.objects.get(owner=user)
+
+    assert response.json() == {
+        "override": None,
+        "data": {},
+        "full_name": "David Bowman",
+        "id": str(new_contact.pk),
+        "notes": "",
+        "owner": str(user.pk),
+        "short_name": "Dave",
+    }
+
+
+def test_api_contacts_create_authenticated_successful():
+    """Authenticated users should be able to create contacts."""
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Existing override for another user should not interfere
+    factories.ContactFactory(override=base_contact)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 3
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": str(base_contact.id),
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.override == base_contact
+    assert contact.owner == user
+
+
+@override_settings(ALLOW_API_USER_CREATE=True)
+def test_api_contacts_create_authenticated_existing_override():
+    """
+    Trying to create a contact overriding a contact that is already overridden by the user
+    should receive a 400 error.
+    """
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+    factories.ContactFactory(override=base_contact, owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "notes": "",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 400
+    assert models.Contact.objects.count() == 2
+
+    assert response.json() == {
+        "__all__": ["Contact with this Owner and Override already exists."]
+    }
+
+
+def test_api_contacts_create_authenticated_successful_with_notes():
+    """Authenticated users should be able to create contacts with notes."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+            "notes": "This is a note",
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 1
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "This is a note",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.owner == user
+    assert contact.notes == "This is a note"
+
+
+def test_api_contacts_update_anonymous():
+    """Anonymous users should not be allowed to update a contact."""
+    contact = factories.ContactFactory()
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+    response = APIClient().put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_update_authenticated_owned():
+    """
+    Authenticated users should be allowed to update their own contacts.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user)  # Owned by the logged-in user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_profile():
+    """
+    Authenticated users should be allowed to update their profile contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_other():
+    """
+    Authenticated users should not be allowed to update contacts owned by other users.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory()  # owned by another user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 403
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_delete_list_anonymous():
+    """Anonymous users should not be allowed to delete a list of contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_list_authenticated():
+    """Authenticated users should not be allowed to delete a list of contacts."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    factories.ContactFactory.create_batch(2)
+
+    response = client.delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 405
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_anonymous():
+    """Anonymous users should not be allowed to delete a contact."""
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    response = client.delete(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_public():
+    """
+    Authenticated users should not be allowed to delete a public contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.BaseContactFactory()
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_owner():
+    """
+    Authenticated users should be allowed to delete a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.count() == 0
+    assert models.Contact.objects.filter(id=contact.id).exists() is False
+
+
+def test_api_contacts_delete_authenticated_profile():
+    """
+    Authenticated users should be allowed to delete their profile contact.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.exists() is False
+
+
+def test_api_contacts_delete_authenticated_other():
+    """
+    Authenticated users should not be allowed to delete a contact they don't own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+ 
diff --git a/src/backend/core/tests/contacts/test_core_api_contacts_retrieve.py b/src/backend/core/tests/contacts/test_core_api_contacts_retrieve.py
new file mode 100644
index 0000000..1168a38
--- /dev/null
+++ b/src/backend/core/tests/contacts/test_core_api_contacts_retrieve.py
@@ -0,0 +1,706 @@
+"""
+Test contacts API endpoints in People's core app.
+"""
+
+from django.test.utils import override_settings
+
+import pytest
+from rest_framework.test import APIClient
+
+from core import factories, models
+from core.api.client import serializers
+
+pytestmark = pytest.mark.django_db
+
+
+CONTACT_DATA = {
+    "emails": [
+        {"type": "Work", "value": "john.doe@work.com"},
+        {"type": "Home", "value": "john.doe@home.com"},
+    ],
+    "phones": [
+        {"type": "Work", "value": "(123) 456-7890"},
+        {"type": "Other", "value": "(987) 654-3210"},
+    ],
+    "addresses": [
+        {
+            "type": "Home",
+            "street": "123 Main St",
+            "city": "Cityville",
+            "state": "CA",
+            "zip": "12345",
+            "country": "USA",
+        }
+    ],
+    "links": [
+        {"type": "Blog", "value": "http://personalwebsite.com"},
+        {"type": "Website", "value": "http://workwebsite.com"},
+    ],
+    "customFields": {"custom_field_1": "value1", "custom_field_2": "value2"},
+    "organizations": [
+        {
+            "name": "ACME Corporation",
+            "department": "IT",
+            "jobTitle": "Software Engineer",
+        },
+        {
+            "name": "XYZ Ltd",
+            "department": "Marketing",
+            "jobTitle": "Marketing Specialist",
+        },
+    ],
+}
+
+
+def test_api_contacts_list_anonymous():
+    """Anonymous users should not be allowed to list contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().get("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_list_authenticated_no_query():
+    """
+    Authenticated users should be able to list contacts without applying a query.
+    Profile and overridden contacts should be excluded.
+    """
+    user = factories.UserFactory()
+    factories.ContactFactory(owner=user, user=user)
+
+    # Let's have 5 contacts in database:
+    assert user.profile_contact is not None  # Excluded because profile contact
+    base_contact = factories.BaseContactFactory()  # Excluded because overridden
+    factories.ContactFactory(
+        override=base_contact
+    )  # Excluded because belongs to other user
+    contact2 = factories.ContactFactory(
+        override=base_contact, owner=user, full_name="Bernard"
+    )  # Included
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/")
+
+    assert response.status_code == 200
+    assert response.json() == [
+        {
+            "id": str(contact2.id),
+            "override": str(base_contact.id),
+            "owner": str(contact2.owner.id),
+            "data": contact2.data,
+            "full_name": contact2.full_name,
+            "notes": "",
+            "short_name": contact2.short_name,
+        },
+    ]
+
+
+def test_api_contacts_list_authenticated_by_full_name():
+    """
+    Authenticated users should be able to search users with a case insensitive and
+    partial query on the full name.
+    """
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="David Bowman")
+    nicole = factories.BaseContactFactory(full_name="Nicole Foole")
+    frank = factories.BaseContactFactory(full_name="Frank Poole")
+    factories.BaseContactFactory(full_name="Heywood Floyd")
+
+    # Full query should work
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=David%20Bowman")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Partial query should work
+    response = client.get("/api/v1.0/contacts/?q=ank")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ole")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ool")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+
+def test_api_contacts_list_authenticated_uppercase_content():
+    """Upper case content should be found by lower case query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="EEE", short_name="AAA")
+
+    # Unaccented full name
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_capital_query():
+    """Upper case query should find lower case content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=EEE")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=AAA")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_content():
+    """Accented content should be found by unaccented query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="ééé", short_name="ààà")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_query():
+    """Accented query should find unaccented content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=ééé")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=ààà")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_retrieve_anonymous():
+    """Anonymous users should not be allowed to retrieve a user."""
+    client = APIClient()
+    contact = factories.ContactFactory()
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_retrieve_authenticated_owned():
+    """
+    Authenticated users should be allowed to retrieve a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": str(contact.owner.id),
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_public():
+    """
+    Authenticated users should be able to retrieve public contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": None,
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_other():
+    """
+    Authenticated users should not be allowed to retrieve another user's contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 403
+    assert response.json() == {
+        "detail": "You do not have permission to perform this action."
+    }
+
+
+def test_api_contacts_create_anonymous_forbidden():
+    """Anonymous users should not be able to create contacts via the API."""
+    response = APIClient().post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David",
+            "short_name": "Bowman",
+        },
+    )
+    assert response.status_code == 401
+    assert not models.Contact.objects.exists()
+
+
+def test_api_contacts_create_authenticated_missing_base():
+    """Authenticated user should be able to create contact without override."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": {},
+        },
+        format="json",
+    )
+    assert response.status_code == 201
+
+    new_contact = models.Contact.objects.get(owner=user)
+
+    assert response.json() == {
+        "override": None,
+        "data": {},
+        "full_name": "David Bowman",
+        "id": str(new_contact.pk),
+        "notes": "",
+        "owner": str(user.pk),
+        "short_name": "Dave",
+    }
+
+
+def test_api_contacts_create_authenticated_successful():
+    """Authenticated users should be able to create contacts."""
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Existing override for another user should not interfere
+    factories.ContactFactory(override=base_contact)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 3
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": str(base_contact.id),
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.override == base_contact
+    assert contact.owner == user
+
+
+@override_settings(ALLOW_API_USER_CREATE=True)
+def test_api_contacts_create_authenticated_existing_override():
+    """
+    Trying to create a contact overriding a contact that is already overridden by the user
+    should receive a 400 error.
+    """
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+    factories.ContactFactory(override=base_contact, owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "notes": "",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 400
+    assert models.Contact.objects.count() == 2
+
+    assert response.json() == {
+        "__all__": ["Contact with this Owner and Override already exists."]
+    }
+
+
+def test_api_contacts_create_authenticated_successful_with_notes():
+    """Authenticated users should be able to create contacts with notes."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+            "notes": "This is a note",
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 1
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "This is a note",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.owner == user
+    assert contact.notes == "This is a note"
+
+
+def test_api_contacts_update_anonymous():
+    """Anonymous users should not be allowed to update a contact."""
+    contact = factories.ContactFactory()
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+    response = APIClient().put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_update_authenticated_owned():
+    """
+    Authenticated users should be allowed to update their own contacts.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user)  # Owned by the logged-in user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_profile():
+    """
+    Authenticated users should be allowed to update their profile contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_other():
+    """
+    Authenticated users should not be allowed to update contacts owned by other users.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory()  # owned by another user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 403
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_delete_list_anonymous():
+    """Anonymous users should not be allowed to delete a list of contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_list_authenticated():
+    """Authenticated users should not be allowed to delete a list of contacts."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    factories.ContactFactory.create_batch(2)
+
+    response = client.delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 405
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_anonymous():
+    """Anonymous users should not be allowed to delete a contact."""
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    response = client.delete(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_public():
+    """
+    Authenticated users should not be allowed to delete a public contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.BaseContactFactory()
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_owner():
+    """
+    Authenticated users should be allowed to delete a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.count() == 0
+    assert models.Contact.objects.filter(id=contact.id).exists() is False
+
+
+def test_api_contacts_delete_authenticated_profile():
+    """
+    Authenticated users should be allowed to delete their profile contact.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.exists() is False
+
+
+def test_api_contacts_delete_authenticated_other():
+    """
+    Authenticated users should not be allowed to delete a contact they don't own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+ 
diff --git a/src/backend/core/tests/contacts/test_core_api_contacts_update.py b/src/backend/core/tests/contacts/test_core_api_contacts_update.py
new file mode 100644
index 0000000..1168a38
--- /dev/null
+++ b/src/backend/core/tests/contacts/test_core_api_contacts_update.py
@@ -0,0 +1,706 @@
+"""
+Test contacts API endpoints in People's core app.
+"""
+
+from django.test.utils import override_settings
+
+import pytest
+from rest_framework.test import APIClient
+
+from core import factories, models
+from core.api.client import serializers
+
+pytestmark = pytest.mark.django_db
+
+
+CONTACT_DATA = {
+    "emails": [
+        {"type": "Work", "value": "john.doe@work.com"},
+        {"type": "Home", "value": "john.doe@home.com"},
+    ],
+    "phones": [
+        {"type": "Work", "value": "(123) 456-7890"},
+        {"type": "Other", "value": "(987) 654-3210"},
+    ],
+    "addresses": [
+        {
+            "type": "Home",
+            "street": "123 Main St",
+            "city": "Cityville",
+            "state": "CA",
+            "zip": "12345",
+            "country": "USA",
+        }
+    ],
+    "links": [
+        {"type": "Blog", "value": "http://personalwebsite.com"},
+        {"type": "Website", "value": "http://workwebsite.com"},
+    ],
+    "customFields": {"custom_field_1": "value1", "custom_field_2": "value2"},
+    "organizations": [
+        {
+            "name": "ACME Corporation",
+            "department": "IT",
+            "jobTitle": "Software Engineer",
+        },
+        {
+            "name": "XYZ Ltd",
+            "department": "Marketing",
+            "jobTitle": "Marketing Specialist",
+        },
+    ],
+}
+
+
+def test_api_contacts_list_anonymous():
+    """Anonymous users should not be allowed to list contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().get("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_list_authenticated_no_query():
+    """
+    Authenticated users should be able to list contacts without applying a query.
+    Profile and overridden contacts should be excluded.
+    """
+    user = factories.UserFactory()
+    factories.ContactFactory(owner=user, user=user)
+
+    # Let's have 5 contacts in database:
+    assert user.profile_contact is not None  # Excluded because profile contact
+    base_contact = factories.BaseContactFactory()  # Excluded because overridden
+    factories.ContactFactory(
+        override=base_contact
+    )  # Excluded because belongs to other user
+    contact2 = factories.ContactFactory(
+        override=base_contact, owner=user, full_name="Bernard"
+    )  # Included
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/")
+
+    assert response.status_code == 200
+    assert response.json() == [
+        {
+            "id": str(contact2.id),
+            "override": str(base_contact.id),
+            "owner": str(contact2.owner.id),
+            "data": contact2.data,
+            "full_name": contact2.full_name,
+            "notes": "",
+            "short_name": contact2.short_name,
+        },
+    ]
+
+
+def test_api_contacts_list_authenticated_by_full_name():
+    """
+    Authenticated users should be able to search users with a case insensitive and
+    partial query on the full name.
+    """
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="David Bowman")
+    nicole = factories.BaseContactFactory(full_name="Nicole Foole")
+    frank = factories.BaseContactFactory(full_name="Frank Poole")
+    factories.BaseContactFactory(full_name="Heywood Floyd")
+
+    # Full query should work
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=David%20Bowman")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Partial query should work
+    response = client.get("/api/v1.0/contacts/?q=ank")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ole")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+    response = client.get("/api/v1.0/contacts/?q=ool")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(frank.id), str(nicole.id)]
+
+
+def test_api_contacts_list_authenticated_uppercase_content():
+    """Upper case content should be found by lower case query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="EEE", short_name="AAA")
+
+    # Unaccented full name
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_capital_query():
+    """Upper case query should find lower case content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=EEE")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=AAA")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_content():
+    """Accented content should be found by unaccented query."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="ééé", short_name="ààà")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=eee")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=aaa")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_list_authenticated_accented_query():
+    """Accented query should find unaccented content."""
+    user = factories.UserFactory()
+
+    dave = factories.BaseContactFactory(full_name="eee", short_name="aaa")
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Unaccented full name
+    response = client.get("/api/v1.0/contacts/?q=ééé")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+    # Unaccented short name
+    response = client.get("/api/v1.0/contacts/?q=ààà")
+
+    assert response.status_code == 200
+    contact_ids = [contact["id"] for contact in response.json()]
+    assert contact_ids == [str(dave.id)]
+
+
+def test_api_contacts_retrieve_anonymous():
+    """Anonymous users should not be allowed to retrieve a user."""
+    client = APIClient()
+    contact = factories.ContactFactory()
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+
+def test_api_contacts_retrieve_authenticated_owned():
+    """
+    Authenticated users should be allowed to retrieve a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": str(contact.owner.id),
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_public():
+    """
+    Authenticated users should be able to retrieve public contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 200
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "owner": None,
+        "data": contact.data,
+        "full_name": contact.full_name,
+        "notes": "",
+        "short_name": contact.short_name,
+    }
+
+
+def test_api_contacts_retrieve_authenticated_other():
+    """
+    Authenticated users should not be allowed to retrieve another user's contacts.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.get(f"/api/v1.0/contacts/{contact.id!s}/")
+    assert response.status_code == 403
+    assert response.json() == {
+        "detail": "You do not have permission to perform this action."
+    }
+
+
+def test_api_contacts_create_anonymous_forbidden():
+    """Anonymous users should not be able to create contacts via the API."""
+    response = APIClient().post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David",
+            "short_name": "Bowman",
+        },
+    )
+    assert response.status_code == 401
+    assert not models.Contact.objects.exists()
+
+
+def test_api_contacts_create_authenticated_missing_base():
+    """Authenticated user should be able to create contact without override."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": {},
+        },
+        format="json",
+    )
+    assert response.status_code == 201
+
+    new_contact = models.Contact.objects.get(owner=user)
+
+    assert response.json() == {
+        "override": None,
+        "data": {},
+        "full_name": "David Bowman",
+        "id": str(new_contact.pk),
+        "notes": "",
+        "owner": str(user.pk),
+        "short_name": "Dave",
+    }
+
+
+def test_api_contacts_create_authenticated_successful():
+    """Authenticated users should be able to create contacts."""
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    # Existing override for another user should not interfere
+    factories.ContactFactory(override=base_contact)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 3
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": str(base_contact.id),
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.override == base_contact
+    assert contact.owner == user
+
+
+@override_settings(ALLOW_API_USER_CREATE=True)
+def test_api_contacts_create_authenticated_existing_override():
+    """
+    Trying to create a contact overriding a contact that is already overridden by the user
+    should receive a 400 error.
+    """
+    user = factories.UserFactory()
+    base_contact = factories.BaseContactFactory()
+    factories.ContactFactory(override=base_contact, owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "override": str(base_contact.id),
+            "full_name": "David Bowman",
+            "notes": "",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+        },
+        format="json",
+    )
+
+    assert response.status_code == 400
+    assert models.Contact.objects.count() == 2
+
+    assert response.json() == {
+        "__all__": ["Contact with this Owner and Override already exists."]
+    }
+
+
+def test_api_contacts_create_authenticated_successful_with_notes():
+    """Authenticated users should be able to create contacts with notes."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.post(
+        "/api/v1.0/contacts/",
+        {
+            "full_name": "David Bowman",
+            "short_name": "Dave",
+            "data": CONTACT_DATA,
+            "notes": "This is a note",
+        },
+        format="json",
+    )
+
+    assert response.status_code == 201
+    assert models.Contact.objects.count() == 1
+
+    contact = models.Contact.objects.get(owner=user)
+    assert response.json() == {
+        "id": str(contact.id),
+        "override": None,
+        "data": CONTACT_DATA,
+        "full_name": "David Bowman",
+        "notes": "This is a note",
+        "owner": str(user.id),
+        "short_name": "Dave",
+    }
+
+    assert contact.full_name == "David Bowman"
+    assert contact.short_name == "Dave"
+    assert contact.data == CONTACT_DATA
+    assert contact.owner == user
+    assert contact.notes == "This is a note"
+
+
+def test_api_contacts_update_anonymous():
+    """Anonymous users should not be allowed to update a contact."""
+    contact = factories.ContactFactory()
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+    response = APIClient().put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+    assert response.status_code == 401
+    assert response.json() == {
+        "detail": "Authentication credentials were not provided."
+    }
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_update_authenticated_owned():
+    """
+    Authenticated users should be allowed to update their own contacts.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user)  # Owned by the logged-in user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_profile():
+    """
+    Authenticated users should be allowed to update their profile contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 200
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    for key, value in contact_values.items():
+        if key in ["override", "owner", "id"]:
+            assert value == old_contact_values[key]
+        else:
+            assert value == new_contact_values[key]
+
+
+def test_api_contacts_update_authenticated_other():
+    """
+    Authenticated users should not be allowed to update contacts owned by other users.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.ContactFactory()  # owned by another user
+    old_contact_values = serializers.ContactSerializer(instance=contact).data
+
+    new_contact_values = serializers.ContactSerializer(
+        instance=factories.ContactFactory()
+    ).data
+    new_contact_values["override"] = str(factories.ContactFactory().id)
+
+    response = client.put(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+        new_contact_values,
+        format="json",
+    )
+
+    assert response.status_code == 403
+
+    contact.refresh_from_db()
+    contact_values = serializers.ContactSerializer(instance=contact).data
+    assert contact_values == old_contact_values
+
+
+def test_api_contacts_delete_list_anonymous():
+    """Anonymous users should not be allowed to delete a list of contacts."""
+    factories.ContactFactory.create_batch(2)
+
+    response = APIClient().delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_list_authenticated():
+    """Authenticated users should not be allowed to delete a list of contacts."""
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    factories.ContactFactory.create_batch(2)
+
+    response = client.delete("/api/v1.0/contacts/")
+
+    assert response.status_code == 405
+    assert models.Contact.objects.count() == 2
+
+
+def test_api_contacts_delete_anonymous():
+    """Anonymous users should not be allowed to delete a contact."""
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    response = client.delete(f"/api/v1.0/contacts/{contact.id!s}/")
+
+    assert response.status_code == 401
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_public():
+    """
+    Authenticated users should not be allowed to delete a public contact.
+    """
+    user = factories.UserFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    contact = factories.BaseContactFactory()
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+
+
+def test_api_contacts_delete_authenticated_owner():
+    """
+    Authenticated users should be allowed to delete a contact they own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.count() == 0
+    assert models.Contact.objects.filter(id=contact.id).exists() is False
+
+
+def test_api_contacts_delete_authenticated_profile():
+    """
+    Authenticated users should be allowed to delete their profile contact.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory(owner=user, user=user)
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 204
+    assert models.Contact.objects.exists() is False
+
+
+def test_api_contacts_delete_authenticated_other():
+    """
+    Authenticated users should not be allowed to delete a contact they don't own.
+    """
+    user = factories.UserFactory()
+    contact = factories.ContactFactory()
+
+    client = APIClient()
+    client.force_login(user)
+
+    response = client.delete(
+        f"/api/v1.0/contacts/{contact.id!s}/",
+    )
+
+    assert response.status_code == 403
+    assert models.Contact.objects.count() == 1
+