diff --git a/src/api/client/account.rs b/src/api/client/account.rs
index 59998292..a7b56e2b 100644
--- a/src/api/client/account.rs
+++ b/src/api/client/account.rs
@@ -1,29 +1,23 @@
-use std::fmt::Write;
-
 use axum::extract::State;
 use axum_client_ip::InsecureClientIp;
 use futures::{FutureExt, StreamExt};
-use register::RegistrationKind;
 use ruma::{
 	OwnedRoomId, UserId,
 	api::client::{
 		account::{
-			ThirdPartyIdRemovalStatus, change_password, check_registration_token_validity,
-			deactivate, get_3pids, get_username_availability,
-			register::{self, LoginType},
+			ThirdPartyIdRemovalStatus, change_password, deactivate, get_3pids,
 			request_3pid_management_token_via_email, request_3pid_management_token_via_msisdn,
 			whoami,
 		},
 		uiaa::{AuthFlow, AuthType, UiaaInfo},
 	},
 	events::{
-		GlobalAccountDataEventType, StateEventType,
+		StateEventType,
 		room::power_levels::{RoomPowerLevels, RoomPowerLevelsEventContent},
 	},
-	push,
 };
 use tuwunel_core::{
-	Err, Error, Result, debug_info, err, error, info, is_equal_to,
+	Err, Error, Result, err, info,
 	matrix::{Event, pdu::PduBuilder},
 	utils,
 	utils::{ReadyExt, stream::BroadbandExt},
@@ -31,570 +25,9 @@ use tuwunel_core::{
 };
 use tuwunel_service::Services;
 
-use super::{DEVICE_ID_LENGTH, SESSION_ID_LENGTH, TOKEN_LENGTH, join_room_by_id_helper};
+use super::SESSION_ID_LENGTH;
 use crate::Ruma;
 
-const RANDOM_USER_ID_LENGTH: usize = 10;
-
-/// # `GET /_matrix/client/v3/register/available`
-///
-/// Checks if a username is valid and available on this server.
-///
-/// Conditions for returning true:
-/// - The user id is not historical
-/// - The server name of the user id matches this server
-/// - No user or appservice on this server already claimed this username
-///
-/// Note: This will not reserve the username, so the username might become
-/// invalid when trying to register
-#[tracing::instrument(skip_all, fields(%client), name = "register_available")]
-pub(crate) async fn get_register_available_route(
-	State(services): State<crate::State>,
-	InsecureClientIp(client): InsecureClientIp,
-	body: Ruma<get_username_availability::v3::Request>,
-) -> Result<get_username_availability::v3::Response> {
-	// workaround for https://github.com/matrix-org/matrix-appservice-irc/issues/1780 due to inactivity of fixing the issue
-	let is_matrix_appservice_irc = body
-		.appservice_info
-		.as_ref()
-		.is_some_and(|appservice| {
-			appservice.registration.id == "irc"
-				|| appservice
-					.registration
-					.id
-					.contains("matrix-appservice-irc")
-				|| appservice
-					.registration
-					.id
-					.contains("matrix_appservice_irc")
-		});
-
-	if services
-		.globals
-		.forbidden_usernames()
-		.is_match(&body.username)
-	{
-		return Err!(Request(Forbidden("Username is forbidden")));
-	}
-
-	// don't force the username lowercase if it's from matrix-appservice-irc
-	let body_username = if is_matrix_appservice_irc {
-		body.username.clone()
-	} else {
-		body.username.to_lowercase()
-	};
-
-	// Validate user id
-	let user_id =
-		match UserId::parse_with_server_name(&body_username, services.globals.server_name()) {
-			| Ok(user_id) => {
-				if let Err(e) = user_id.validate_strict() {
-					// unless the username is from the broken matrix appservice IRC bridge, we
-					// should follow synapse's behaviour on not allowing things like spaces
-					// and UTF-8 characters in usernames
-					if !is_matrix_appservice_irc {
-						return Err!(Request(InvalidUsername(debug_warn!(
-							"Username {body_username} contains disallowed characters or spaces: \
-							 {e}"
-						))));
-					}
-				}
-
-				user_id
-			},
-			| Err(e) => {
-				return Err!(Request(InvalidUsername(debug_warn!(
-					"Username {body_username} is not valid: {e}"
-				))));
-			},
-		};
-
-	// Check if username is creative enough
-	if services.users.exists(&user_id).await {
-		return Err!(Request(UserInUse("User ID is not available.")));
-	}
-
-	if let Some(ref info) = body.appservice_info {
-		if !info.is_user_match(&user_id) {
-			return Err!(Request(Exclusive("Username is not in an appservice namespace.")));
-		}
-	}
-
-	if services
-		.appservice
-		.is_exclusive_user_id(&user_id)
-		.await
-	{
-		return Err!(Request(Exclusive("Username is reserved by an appservice.")));
-	}
-
-	Ok(get_username_availability::v3::Response { available: true })
-}
-
-/// # `POST /_matrix/client/v3/register`
-///
-/// Register an account on this homeserver.
-///
-/// You can use [`GET
-/// /_matrix/client/v3/register/available`](fn.get_register_available_route.
-/// html) to check if the user id is valid and available.
-///
-/// - Only works if registration is enabled
-/// - If type is guest: ignores all parameters except
-///   initial_device_display_name
-/// - If sender is not appservice: Requires UIAA (but we only use a dummy stage)
-/// - If type is not guest and no username is given: Always fails after UIAA
-///   check
-/// - Creates a new account and populates it with default account data
-/// - If `inhibit_login` is false: Creates a device and returns device id and
-///   access_token
-#[allow(clippy::doc_markdown)]
-#[tracing::instrument(skip_all, fields(%client), name = "register")]
-pub(crate) async fn register_route(
-	State(services): State<crate::State>,
-	InsecureClientIp(client): InsecureClientIp,
-	body: Ruma<register::v3::Request>,
-) -> Result<register::v3::Response> {
-	let is_guest = body.kind == RegistrationKind::Guest;
-	let emergency_mode_enabled = services.config.emergency_password.is_some();
-
-	if !services.config.allow_registration && body.appservice_info.is_none() {
-		match (body.username.as_ref(), body.initial_device_display_name.as_ref()) {
-			| (Some(username), Some(device_display_name)) => {
-				info!(
-					%is_guest,
-					user = %username,
-					device_name = %device_display_name,
-					"Rejecting registration attempt as registration is disabled"
-				);
-			},
-			| (Some(username), _) => {
-				info!(
-					%is_guest,
-					user = %username,
-					"Rejecting registration attempt as registration is disabled"
-				);
-			},
-			| (_, Some(device_display_name)) => {
-				info!(
-					%is_guest,
-					device_name = %device_display_name,
-					"Rejecting registration attempt as registration is disabled"
-				);
-			},
-			| (None, _) => {
-				info!(
-					%is_guest,
-					"Rejecting registration attempt as registration is disabled"
-				);
-			},
-		}
-
-		return Err!(Request(Forbidden("Registration has been disabled.")));
-	}
-
-	if is_guest
-		&& (!services.config.allow_guest_registration
-			|| (services.config.allow_registration
-				&& services.globals.registration_token.is_some()))
-	{
-		info!(
-			"Guest registration disabled / registration enabled with token configured, \
-			 rejecting guest registration attempt, initial device name: \"{}\"",
-			body.initial_device_display_name
-				.as_deref()
-				.unwrap_or("")
-		);
-		return Err!(Request(GuestAccessForbidden("Guest registration is disabled.")));
-	}
-
-	// forbid guests from registering if there is not a real admin user yet. give
-	// generic user error.
-	if is_guest && services.users.count().await < 2 {
-		warn!(
-			"Guest account attempted to register before a real admin user has been registered, \
-			 rejecting registration. Guest's initial device name: \"{}\"",
-			body.initial_device_display_name
-				.as_deref()
-				.unwrap_or("")
-		);
-		return Err!(Request(Forbidden("Registration is temporarily disabled.")));
-	}
-
-	let user_id = match (body.username.as_ref(), is_guest) {
-		| (Some(username), false) => {
-			// workaround for https://github.com/matrix-org/matrix-appservice-irc/issues/1780 due to inactivity of fixing the issue
-			let is_matrix_appservice_irc =
-				body.appservice_info
-					.as_ref()
-					.is_some_and(|appservice| {
-						appservice.registration.id == "irc"
-							|| appservice
-								.registration
-								.id
-								.contains("matrix-appservice-irc")
-							|| appservice
-								.registration
-								.id
-								.contains("matrix_appservice_irc")
-					});
-
-			if services
-				.globals
-				.forbidden_usernames()
-				.is_match(username)
-				&& !emergency_mode_enabled
-			{
-				return Err!(Request(Forbidden("Username is forbidden")));
-			}
-
-			// don't force the username lowercase if it's from matrix-appservice-irc
-			let body_username = if is_matrix_appservice_irc {
-				username.clone()
-			} else {
-				username.to_lowercase()
-			};
-
-			let proposed_user_id = match UserId::parse_with_server_name(
-				&body_username,
-				services.globals.server_name(),
-			) {
-				| Ok(user_id) => {
-					if let Err(e) = user_id.validate_strict() {
-						// unless the username is from the broken matrix appservice IRC bridge, or
-						// we are in emergency mode, we should follow synapse's behaviour on
-						// not allowing things like spaces and UTF-8 characters in usernames
-						if !is_matrix_appservice_irc && !emergency_mode_enabled {
-							return Err!(Request(InvalidUsername(debug_warn!(
-								"Username {body_username} contains disallowed characters or \
-								 spaces: {e}"
-							))));
-						}
-					}
-
-					user_id
-				},
-				| Err(e) => {
-					return Err!(Request(InvalidUsername(debug_warn!(
-						"Username {body_username} is not valid: {e}"
-					))));
-				},
-			};
-
-			if services.users.exists(&proposed_user_id).await {
-				return Err!(Request(UserInUse("User ID is not available.")));
-			}
-
-			proposed_user_id
-		},
-		| _ => loop {
-			let proposed_user_id = UserId::parse_with_server_name(
-				utils::random_string(RANDOM_USER_ID_LENGTH).to_lowercase(),
-				services.globals.server_name(),
-			)
-			.unwrap();
-			if !services.users.exists(&proposed_user_id).await {
-				break proposed_user_id;
-			}
-		},
-	};
-
-	if body.body.login_type == Some(LoginType::ApplicationService) {
-		match body.appservice_info {
-			| Some(ref info) =>
-				if !info.is_user_match(&user_id) && !emergency_mode_enabled {
-					return Err!(Request(Exclusive(
-						"Username is not in an appservice namespace."
-					)));
-				},
-			| _ => {
-				return Err!(Request(MissingToken("Missing appservice token.")));
-			},
-		}
-	} else if services
-		.appservice
-		.is_exclusive_user_id(&user_id)
-		.await && !emergency_mode_enabled
-	{
-		return Err!(Request(Exclusive("Username is reserved by an appservice.")));
-	}
-
-	// UIAA
-	let mut uiaainfo;
-	let skip_auth = if services.globals.registration_token.is_some() {
-		// Registration token required
-		uiaainfo = UiaaInfo {
-			flows: vec![AuthFlow {
-				stages: vec![AuthType::RegistrationToken],
-			}],
-			completed: Vec::new(),
-			params: Box::default(),
-			session: None,
-			auth_error: None,
-		};
-		body.appservice_info.is_some()
-	} else {
-		// No registration token necessary, but clients must still go through the flow
-		uiaainfo = UiaaInfo {
-			flows: vec![AuthFlow { stages: vec![AuthType::Dummy] }],
-			completed: Vec::new(),
-			params: Box::default(),
-			session: None,
-			auth_error: None,
-		};
-		body.appservice_info.is_some() || is_guest
-	};
-
-	if !skip_auth {
-		match &body.auth {
-			| Some(auth) => {
-				let (worked, uiaainfo) = services
-					.uiaa
-					.try_auth(
-						&UserId::parse_with_server_name("", services.globals.server_name())
-							.unwrap(),
-						"".into(),
-						auth,
-						&uiaainfo,
-					)
-					.await?;
-				if !worked {
-					return Err(Error::Uiaa(uiaainfo));
-				}
-				// Success!
-			},
-			| _ => match body.json_body {
-				| Some(ref json) => {
-					uiaainfo.session = Some(utils::random_string(SESSION_ID_LENGTH));
-					services.uiaa.create(
-						&UserId::parse_with_server_name("", services.globals.server_name())
-							.unwrap(),
-						"".into(),
-						&uiaainfo,
-						json,
-					);
-					return Err(Error::Uiaa(uiaainfo));
-				},
-				| _ => {
-					return Err!(Request(NotJson("JSON body is not valid")));
-				},
-			},
-		}
-	}
-
-	let password = if is_guest { None } else { body.password.as_deref() };
-
-	// Create user
-	services
-		.users
-		.create(&user_id, password, None)
-		.await?;
-
-	// Default to pretty displayname
-	let mut displayname = user_id.localpart().to_owned();
-
-	// If `new_user_displayname_suffix` is set, registration will push whatever
-	// content is set to the user's display name with a space before it
-	if !services
-		.globals
-		.new_user_displayname_suffix()
-		.is_empty()
-		&& body.appservice_info.is_none()
-	{
-		write!(displayname, " {}", services.server.config.new_user_displayname_suffix)?;
-	}
-
-	services
-		.users
-		.set_displayname(&user_id, Some(displayname.clone()));
-
-	// Initial account data
-	services
-		.account_data
-		.update(
-			None,
-			&user_id,
-			GlobalAccountDataEventType::PushRules
-				.to_string()
-				.into(),
-			&serde_json::to_value(ruma::events::push_rules::PushRulesEvent {
-				content: ruma::events::push_rules::PushRulesEventContent {
-					global: push::Ruleset::server_default(&user_id),
-				},
-			})?,
-		)
-		.await?;
-
-	if (!is_guest && body.inhibit_login)
-		|| body
-			.appservice_info
-			.as_ref()
-			.is_some_and(|appservice| appservice.registration.device_management)
-	{
-		return Ok(register::v3::Response {
-			access_token: None,
-			user_id,
-			device_id: None,
-			refresh_token: None,
-			expires_in: None,
-		});
-	}
-
-	// Generate new device id if the user didn't specify one
-	let device_id = if is_guest { None } else { body.device_id.clone() }
-		.unwrap_or_else(|| utils::random_string(DEVICE_ID_LENGTH).into());
-
-	// Generate new token for the device
-	let token = utils::random_string(TOKEN_LENGTH);
-
-	// Create device for this account
-	services
-		.users
-		.create_device(
-			&user_id,
-			&device_id,
-			&token,
-			body.initial_device_display_name.clone(),
-			Some(client.to_string()),
-		)
-		.await?;
-
-	debug_info!(%user_id, %device_id, "User account was created");
-
-	let device_display_name = body
-		.initial_device_display_name
-		.as_deref()
-		.unwrap_or("");
-
-	// log in conduit admin channel if a non-guest user registered
-	if body.appservice_info.is_none() && !is_guest {
-		if !device_display_name.is_empty() {
-			let notice = format!(
-				"New user \"{user_id}\" registered on this server from IP {client} and device \
-				 display name \"{device_display_name}\""
-			);
-
-			info!("{notice}");
-			if services.server.config.admin_room_notices {
-				services.admin.notice(&notice).await;
-			}
-		} else {
-			let notice = format!("New user \"{user_id}\" registered on this server.");
-
-			info!("{notice}");
-			if services.server.config.admin_room_notices {
-				services.admin.notice(&notice).await;
-			}
-		}
-	}
-
-	// log in conduit admin channel if a guest registered
-	if body.appservice_info.is_none() && is_guest && services.config.log_guest_registrations {
-		debug_info!("New guest user \"{user_id}\" registered on this server.");
-
-		if !device_display_name.is_empty() {
-			if services.server.config.admin_room_notices {
-				services
-					.admin
-					.notice(&format!(
-						"Guest user \"{user_id}\" with device display name \
-						 \"{device_display_name}\" registered on this server from IP {client}"
-					))
-					.await;
-			}
-		} else {
-			#[allow(clippy::collapsible_else_if)]
-			if services.server.config.admin_room_notices {
-				services
-					.admin
-					.notice(&format!(
-						"Guest user \"{user_id}\" with no device display name registered on \
-						 this server from IP {client}",
-					))
-					.await;
-			}
-		}
-	}
-
-	// If this is the first real user, grant them admin privileges except for guest
-	// users
-	// Note: the server user is generated first
-	if !is_guest {
-		if let Ok(admin_room) = services.admin.get_admin_room().await {
-			if services
-				.rooms
-				.state_cache
-				.room_joined_count(&admin_room)
-				.await
-				.is_ok_and(is_equal_to!(1))
-			{
-				services.admin.make_user_admin(&user_id).await?;
-				warn!("Granting {user_id} admin privileges as the first user");
-			}
-		}
-	}
-
-	if body.appservice_info.is_none()
-		&& !services.server.config.auto_join_rooms.is_empty()
-		&& (services.config.allow_guests_auto_join_rooms || !is_guest)
-	{
-		for room in &services.server.config.auto_join_rooms {
-			let Ok(room_id) = services.rooms.alias.resolve(room).await else {
-				error!(
-					"Failed to resolve room alias to room ID when attempting to auto join \
-					 {room}, skipping"
-				);
-				continue;
-			};
-
-			if !services
-				.rooms
-				.state_cache
-				.server_in_room(services.globals.server_name(), &room_id)
-				.await
-			{
-				warn!(
-					"Skipping room {room} to automatically join as we have never joined before."
-				);
-				continue;
-			}
-
-			if let Some(room_server_name) = room.server_name() {
-				match join_room_by_id_helper(
-					&services,
-					&user_id,
-					&room_id,
-					Some("Automatically joining this room upon registration".to_owned()),
-					&[services.globals.server_name().to_owned(), room_server_name.to_owned()],
-					None,
-					&body.appservice_info,
-				)
-				.boxed()
-				.await
-				{
-					| Err(e) => {
-						// don't return this error so we don't fail registrations
-						error!(
-							"Failed to automatically join room {room} for user {user_id}: {e}"
-						);
-					},
-					| _ => {
-						info!("Automatically joined room {room} for user {user_id}");
-					},
-				}
-			}
-		}
-	}
-
-	Ok(register::v3::Response {
-		access_token: Some(token),
-		user_id,
-		device_id: Some(device_id),
-		refresh_token: None,
-		expires_in: None,
-	})
-}
-
 /// # `POST /_matrix/client/r0/account/password`
 ///
 /// Changes the password of this account.
@@ -861,23 +294,6 @@ pub(crate) async fn request_3pid_management_token_via_msisdn_route(
 	Err!(Request(ThreepidDenied("Third party identifiers are not implemented")))
 }
 
-/// # `GET /_matrix/client/v1/register/m.login.registration_token/validity`
-///
-/// Checks if the provided registration token is valid at the time of checking
-///
-/// Currently does not have any ratelimiting, and this isn't very practical as
-/// there is only one registration token allowed.
-pub(crate) async fn check_registration_token_validity(
-	State(services): State<crate::State>,
-	body: Ruma<check_registration_token_validity::v1::Request>,
-) -> Result<check_registration_token_validity::v1::Response> {
-	let Some(reg_token) = services.globals.registration_token.clone() else {
-		return Err!(Request(Forbidden("Server does not allow token registration")));
-	};
-
-	Ok(check_registration_token_validity::v1::Response { valid: reg_token == body.token })
-}
-
 /// Runs through all the deactivation steps:
 ///
 /// - Mark as deactivated
diff --git a/src/api/client/mod.rs b/src/api/client/mod.rs
index ef62f7ec..1b7ed592 100644
--- a/src/api/client/mod.rs
+++ b/src/api/client/mod.rs
@@ -19,6 +19,7 @@ pub(super) mod profile;
 pub(super) mod push;
 pub(super) mod read_marker;
 pub(super) mod redact;
+pub(super) mod register;
 pub(super) mod relations;
 pub(super) mod report;
 pub(super) mod room;
@@ -63,6 +64,7 @@ pub use profile::{update_all_rooms, update_avatar_url, update_displayname};
 pub(super) use push::*;
 pub(super) use read_marker::*;
 pub(super) use redact::*;
+pub(super) use register::*;
 pub(super) use relations::*;
 pub(super) use report::*;
 pub(super) use room::*;
diff --git a/src/api/client/register.rs b/src/api/client/register.rs
new file mode 100644
index 00000000..aa29bb28
--- /dev/null
+++ b/src/api/client/register.rs
@@ -0,0 +1,600 @@
+use std::fmt::Write;
+
+use axum::extract::State;
+use axum_client_ip::InsecureClientIp;
+use futures::FutureExt;
+use register::RegistrationKind;
+use ruma::{
+	UserId,
+	api::client::{
+		account::{
+			check_registration_token_validity, get_username_availability,
+			register::{self, LoginType},
+		},
+		uiaa::{AuthFlow, AuthType, UiaaInfo},
+	},
+	events::GlobalAccountDataEventType,
+	push,
+};
+use tuwunel_core::{Err, Error, Result, debug_info, error, info, is_equal_to, utils, warn};
+
+use super::{DEVICE_ID_LENGTH, SESSION_ID_LENGTH, TOKEN_LENGTH, join_room_by_id_helper};
+use crate::Ruma;
+
+const RANDOM_USER_ID_LENGTH: usize = 10;
+
+/// # `GET /_matrix/client/v3/register/available`
+///
+/// Checks if a username is valid and available on this server.
+///
+/// Conditions for returning true:
+/// - The user id is not historical
+/// - The server name of the user id matches this server
+/// - No user or appservice on this server already claimed this username
+///
+/// Note: This will not reserve the username, so the username might become
+/// invalid when trying to register
+#[tracing::instrument(skip_all, fields(%client), name = "register_available")]
+pub(crate) async fn get_register_available_route(
+	State(services): State<crate::State>,
+	InsecureClientIp(client): InsecureClientIp,
+	body: Ruma<get_username_availability::v3::Request>,
+) -> Result<get_username_availability::v3::Response> {
+	// workaround for https://github.com/matrix-org/matrix-appservice-irc/issues/1780 due to inactivity of fixing the issue
+	let is_matrix_appservice_irc = body
+		.appservice_info
+		.as_ref()
+		.is_some_and(|appservice| {
+			appservice.registration.id == "irc"
+				|| appservice
+					.registration
+					.id
+					.contains("matrix-appservice-irc")
+				|| appservice
+					.registration
+					.id
+					.contains("matrix_appservice_irc")
+		});
+
+	if services
+		.globals
+		.forbidden_usernames()
+		.is_match(&body.username)
+	{
+		return Err!(Request(Forbidden("Username is forbidden")));
+	}
+
+	// don't force the username lowercase if it's from matrix-appservice-irc
+	let body_username = if is_matrix_appservice_irc {
+		body.username.clone()
+	} else {
+		body.username.to_lowercase()
+	};
+
+	// Validate user id
+	let user_id =
+		match UserId::parse_with_server_name(&body_username, services.globals.server_name()) {
+			| Ok(user_id) => {
+				if let Err(e) = user_id.validate_strict() {
+					// unless the username is from the broken matrix appservice IRC bridge, we
+					// should follow synapse's behaviour on not allowing things like spaces
+					// and UTF-8 characters in usernames
+					if !is_matrix_appservice_irc {
+						return Err!(Request(InvalidUsername(debug_warn!(
+							"Username {body_username} contains disallowed characters or spaces: \
+							 {e}"
+						))));
+					}
+				}
+
+				user_id
+			},
+			| Err(e) => {
+				return Err!(Request(InvalidUsername(debug_warn!(
+					"Username {body_username} is not valid: {e}"
+				))));
+			},
+		};
+
+	// Check if username is creative enough
+	if services.users.exists(&user_id).await {
+		return Err!(Request(UserInUse("User ID is not available.")));
+	}
+
+	if let Some(ref info) = body.appservice_info {
+		if !info.is_user_match(&user_id) {
+			return Err!(Request(Exclusive("Username is not in an appservice namespace.")));
+		}
+	}
+
+	if services
+		.appservice
+		.is_exclusive_user_id(&user_id)
+		.await
+	{
+		return Err!(Request(Exclusive("Username is reserved by an appservice.")));
+	}
+
+	Ok(get_username_availability::v3::Response { available: true })
+}
+
+/// # `POST /_matrix/client/v3/register`
+///
+/// Register an account on this homeserver.
+///
+/// You can use [`GET
+/// /_matrix/client/v3/register/available`](fn.get_register_available_route.
+/// html) to check if the user id is valid and available.
+///
+/// - Only works if registration is enabled
+/// - If type is guest: ignores all parameters except
+///   initial_device_display_name
+/// - If sender is not appservice: Requires UIAA (but we only use a dummy stage)
+/// - If type is not guest and no username is given: Always fails after UIAA
+///   check
+/// - Creates a new account and populates it with default account data
+/// - If `inhibit_login` is false: Creates a device and returns device id and
+///   access_token
+#[allow(clippy::doc_markdown)]
+#[tracing::instrument(skip_all, fields(%client), name = "register")]
+pub(crate) async fn register_route(
+	State(services): State<crate::State>,
+	InsecureClientIp(client): InsecureClientIp,
+	body: Ruma<register::v3::Request>,
+) -> Result<register::v3::Response> {
+	let is_guest = body.kind == RegistrationKind::Guest;
+	let emergency_mode_enabled = services.config.emergency_password.is_some();
+
+	if !services.config.allow_registration && body.appservice_info.is_none() {
+		match (body.username.as_ref(), body.initial_device_display_name.as_ref()) {
+			| (Some(username), Some(device_display_name)) => {
+				info!(
+					%is_guest,
+					user = %username,
+					device_name = %device_display_name,
+					"Rejecting registration attempt as registration is disabled"
+				);
+			},
+			| (Some(username), _) => {
+				info!(
+					%is_guest,
+					user = %username,
+					"Rejecting registration attempt as registration is disabled"
+				);
+			},
+			| (_, Some(device_display_name)) => {
+				info!(
+					%is_guest,
+					device_name = %device_display_name,
+					"Rejecting registration attempt as registration is disabled"
+				);
+			},
+			| (None, _) => {
+				info!(
+					%is_guest,
+					"Rejecting registration attempt as registration is disabled"
+				);
+			},
+		}
+
+		return Err!(Request(Forbidden("Registration has been disabled.")));
+	}
+
+	if is_guest
+		&& (!services.config.allow_guest_registration
+			|| (services.config.allow_registration
+				&& services.globals.registration_token.is_some()))
+	{
+		info!(
+			"Guest registration disabled / registration enabled with token configured, \
+			 rejecting guest registration attempt, initial device name: \"{}\"",
+			body.initial_device_display_name
+				.as_deref()
+				.unwrap_or("")
+		);
+		return Err!(Request(GuestAccessForbidden("Guest registration is disabled.")));
+	}
+
+	// forbid guests from registering if there is not a real admin user yet. give
+	// generic user error.
+	if is_guest && services.users.count().await < 2 {
+		warn!(
+			"Guest account attempted to register before a real admin user has been registered, \
+			 rejecting registration. Guest's initial device name: \"{}\"",
+			body.initial_device_display_name
+				.as_deref()
+				.unwrap_or("")
+		);
+		return Err!(Request(Forbidden("Registration is temporarily disabled.")));
+	}
+
+	let user_id = match (body.username.as_ref(), is_guest) {
+		| (Some(username), false) => {
+			// workaround for https://github.com/matrix-org/matrix-appservice-irc/issues/1780 due to inactivity of fixing the issue
+			let is_matrix_appservice_irc =
+				body.appservice_info
+					.as_ref()
+					.is_some_and(|appservice| {
+						appservice.registration.id == "irc"
+							|| appservice
+								.registration
+								.id
+								.contains("matrix-appservice-irc")
+							|| appservice
+								.registration
+								.id
+								.contains("matrix_appservice_irc")
+					});
+
+			if services
+				.globals
+				.forbidden_usernames()
+				.is_match(username)
+				&& !emergency_mode_enabled
+			{
+				return Err!(Request(Forbidden("Username is forbidden")));
+			}
+
+			// don't force the username lowercase if it's from matrix-appservice-irc
+			let body_username = if is_matrix_appservice_irc {
+				username.clone()
+			} else {
+				username.to_lowercase()
+			};
+
+			let proposed_user_id = match UserId::parse_with_server_name(
+				&body_username,
+				services.globals.server_name(),
+			) {
+				| Ok(user_id) => {
+					if let Err(e) = user_id.validate_strict() {
+						// unless the username is from the broken matrix appservice IRC bridge, or
+						// we are in emergency mode, we should follow synapse's behaviour on
+						// not allowing things like spaces and UTF-8 characters in usernames
+						if !is_matrix_appservice_irc && !emergency_mode_enabled {
+							return Err!(Request(InvalidUsername(debug_warn!(
+								"Username {body_username} contains disallowed characters or \
+								 spaces: {e}"
+							))));
+						}
+					}
+
+					user_id
+				},
+				| Err(e) => {
+					return Err!(Request(InvalidUsername(debug_warn!(
+						"Username {body_username} is not valid: {e}"
+					))));
+				},
+			};
+
+			if services.users.exists(&proposed_user_id).await {
+				return Err!(Request(UserInUse("User ID is not available.")));
+			}
+
+			proposed_user_id
+		},
+		| _ => loop {
+			let proposed_user_id = UserId::parse_with_server_name(
+				utils::random_string(RANDOM_USER_ID_LENGTH).to_lowercase(),
+				services.globals.server_name(),
+			)
+			.unwrap();
+			if !services.users.exists(&proposed_user_id).await {
+				break proposed_user_id;
+			}
+		},
+	};
+
+	if body.body.login_type == Some(LoginType::ApplicationService) {
+		match body.appservice_info {
+			| Some(ref info) =>
+				if !info.is_user_match(&user_id) && !emergency_mode_enabled {
+					return Err!(Request(Exclusive(
+						"Username is not in an appservice namespace."
+					)));
+				},
+			| _ => {
+				return Err!(Request(MissingToken("Missing appservice token.")));
+			},
+		}
+	} else if services
+		.appservice
+		.is_exclusive_user_id(&user_id)
+		.await && !emergency_mode_enabled
+	{
+		return Err!(Request(Exclusive("Username is reserved by an appservice.")));
+	}
+
+	// UIAA
+	let mut uiaainfo;
+	let skip_auth = if services.globals.registration_token.is_some() {
+		// Registration token required
+		uiaainfo = UiaaInfo {
+			flows: vec![AuthFlow {
+				stages: vec![AuthType::RegistrationToken],
+			}],
+			completed: Vec::new(),
+			params: Box::default(),
+			session: None,
+			auth_error: None,
+		};
+		body.appservice_info.is_some()
+	} else {
+		// No registration token necessary, but clients must still go through the flow
+		uiaainfo = UiaaInfo {
+			flows: vec![AuthFlow { stages: vec![AuthType::Dummy] }],
+			completed: Vec::new(),
+			params: Box::default(),
+			session: None,
+			auth_error: None,
+		};
+		body.appservice_info.is_some() || is_guest
+	};
+
+	if !skip_auth {
+		match &body.auth {
+			| Some(auth) => {
+				let (worked, uiaainfo) = services
+					.uiaa
+					.try_auth(
+						&UserId::parse_with_server_name("", services.globals.server_name())
+							.unwrap(),
+						"".into(),
+						auth,
+						&uiaainfo,
+					)
+					.await?;
+				if !worked {
+					return Err(Error::Uiaa(uiaainfo));
+				}
+				// Success!
+			},
+			| _ => match body.json_body {
+				| Some(ref json) => {
+					uiaainfo.session = Some(utils::random_string(SESSION_ID_LENGTH));
+					services.uiaa.create(
+						&UserId::parse_with_server_name("", services.globals.server_name())
+							.unwrap(),
+						"".into(),
+						&uiaainfo,
+						json,
+					);
+					return Err(Error::Uiaa(uiaainfo));
+				},
+				| _ => {
+					return Err!(Request(NotJson("JSON body is not valid")));
+				},
+			},
+		}
+	}
+
+	let password = if is_guest { None } else { body.password.as_deref() };
+
+	// Create user
+	services
+		.users
+		.create(&user_id, password, None)
+		.await?;
+
+	// Default to pretty displayname
+	let mut displayname = user_id.localpart().to_owned();
+
+	// If `new_user_displayname_suffix` is set, registration will push whatever
+	// content is set to the user's display name with a space before it
+	if !services
+		.globals
+		.new_user_displayname_suffix()
+		.is_empty()
+		&& body.appservice_info.is_none()
+	{
+		write!(displayname, " {}", services.server.config.new_user_displayname_suffix)?;
+	}
+
+	services
+		.users
+		.set_displayname(&user_id, Some(displayname.clone()));
+
+	// Initial account data
+	services
+		.account_data
+		.update(
+			None,
+			&user_id,
+			GlobalAccountDataEventType::PushRules
+				.to_string()
+				.into(),
+			&serde_json::to_value(ruma::events::push_rules::PushRulesEvent {
+				content: ruma::events::push_rules::PushRulesEventContent {
+					global: push::Ruleset::server_default(&user_id),
+				},
+			})?,
+		)
+		.await?;
+
+	if (!is_guest && body.inhibit_login)
+		|| body
+			.appservice_info
+			.as_ref()
+			.is_some_and(|appservice| appservice.registration.device_management)
+	{
+		return Ok(register::v3::Response {
+			access_token: None,
+			user_id,
+			device_id: None,
+			refresh_token: None,
+			expires_in: None,
+		});
+	}
+
+	// Generate new device id if the user didn't specify one
+	let device_id = if is_guest { None } else { body.device_id.clone() }
+		.unwrap_or_else(|| utils::random_string(DEVICE_ID_LENGTH).into());
+
+	// Generate new token for the device
+	let token = utils::random_string(TOKEN_LENGTH);
+
+	// Create device for this account
+	services
+		.users
+		.create_device(
+			&user_id,
+			&device_id,
+			&token,
+			body.initial_device_display_name.clone(),
+			Some(client.to_string()),
+		)
+		.await?;
+
+	debug_info!(%user_id, %device_id, "User account was created");
+
+	let device_display_name = body
+		.initial_device_display_name
+		.as_deref()
+		.unwrap_or("");
+
+	// log in conduit admin channel if a non-guest user registered
+	if body.appservice_info.is_none() && !is_guest {
+		if !device_display_name.is_empty() {
+			let notice = format!(
+				"New user \"{user_id}\" registered on this server from IP {client} and device \
+				 display name \"{device_display_name}\""
+			);
+
+			info!("{notice}");
+			if services.server.config.admin_room_notices {
+				services.admin.notice(&notice).await;
+			}
+		} else {
+			let notice = format!("New user \"{user_id}\" registered on this server.");
+
+			info!("{notice}");
+			if services.server.config.admin_room_notices {
+				services.admin.notice(&notice).await;
+			}
+		}
+	}
+
+	// log in conduit admin channel if a guest registered
+	if body.appservice_info.is_none() && is_guest && services.config.log_guest_registrations {
+		debug_info!("New guest user \"{user_id}\" registered on this server.");
+
+		if !device_display_name.is_empty() {
+			if services.server.config.admin_room_notices {
+				services
+					.admin
+					.notice(&format!(
+						"Guest user \"{user_id}\" with device display name \
+						 \"{device_display_name}\" registered on this server from IP {client}"
+					))
+					.await;
+			}
+		} else {
+			#[allow(clippy::collapsible_else_if)]
+			if services.server.config.admin_room_notices {
+				services
+					.admin
+					.notice(&format!(
+						"Guest user \"{user_id}\" with no device display name registered on \
+						 this server from IP {client}",
+					))
+					.await;
+			}
+		}
+	}
+
+	// If this is the first real user, grant them admin privileges except for guest
+	// users
+	// Note: the server user is generated first
+	if !is_guest {
+		if let Ok(admin_room) = services.admin.get_admin_room().await {
+			if services
+				.rooms
+				.state_cache
+				.room_joined_count(&admin_room)
+				.await
+				.is_ok_and(is_equal_to!(1))
+			{
+				services.admin.make_user_admin(&user_id).await?;
+				warn!("Granting {user_id} admin privileges as the first user");
+			}
+		}
+	}
+
+	if body.appservice_info.is_none()
+		&& !services.server.config.auto_join_rooms.is_empty()
+		&& (services.config.allow_guests_auto_join_rooms || !is_guest)
+	{
+		for room in &services.server.config.auto_join_rooms {
+			let Ok(room_id) = services.rooms.alias.resolve(room).await else {
+				error!(
+					"Failed to resolve room alias to room ID when attempting to auto join \
+					 {room}, skipping"
+				);
+				continue;
+			};
+
+			if !services
+				.rooms
+				.state_cache
+				.server_in_room(services.globals.server_name(), &room_id)
+				.await
+			{
+				warn!(
+					"Skipping room {room} to automatically join as we have never joined before."
+				);
+				continue;
+			}
+
+			if let Some(room_server_name) = room.server_name() {
+				match join_room_by_id_helper(
+					&services,
+					&user_id,
+					&room_id,
+					Some("Automatically joining this room upon registration".to_owned()),
+					&[services.globals.server_name().to_owned(), room_server_name.to_owned()],
+					None,
+					&body.appservice_info,
+				)
+				.boxed()
+				.await
+				{
+					| Err(e) => {
+						// don't return this error so we don't fail registrations
+						error!(
+							"Failed to automatically join room {room} for user {user_id}: {e}"
+						);
+					},
+					| _ => {
+						info!("Automatically joined room {room} for user {user_id}");
+					},
+				}
+			}
+		}
+	}
+
+	Ok(register::v3::Response {
+		access_token: Some(token),
+		user_id,
+		device_id: Some(device_id),
+		refresh_token: None,
+		expires_in: None,
+	})
+}
+
+/// # `GET /_matrix/client/v1/register/m.login.registration_token/validity`
+///
+/// Checks if the provided registration token is valid at the time of checking
+///
+/// Currently does not have any ratelimiting, and this isn't very practical as
+/// there is only one registration token allowed.
+pub(crate) async fn check_registration_token_validity(
+	State(services): State<crate::State>,
+	body: Ruma<check_registration_token_validity::v1::Request>,
+) -> Result<check_registration_token_validity::v1::Response> {
+	let Some(reg_token) = services.globals.registration_token.clone() else {
+		return Err!(Request(Forbidden("Server does not allow token registration")));
+	};
+
+	Ok(check_registration_token_validity::v1::Response { valid: reg_token == body.token })
+}