diff --git a/lib/pleroma/domain.ex b/lib/pleroma/domain.ex
new file mode 100644
index 000000000..d708188ee
--- /dev/null
+++ b/lib/pleroma/domain.ex
@@ -0,0 +1,53 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2023 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+defmodule Pleroma.Domain do
+  use Ecto.Schema
+
+  import Ecto.Changeset
+
+  alias Pleroma.Repo
+
+  schema "domains" do
+    field(:domain, :string, default: "")
+    field(:public, :boolean, default: false)
+
+    timestamps()
+  end
+
+  def changeset(%__MODULE__{} = domain, params \\ %{}) do
+    domain
+    |> cast(params, [:domain, :public])
+    |> validate_required([:domain])
+  end
+
+  def update_changeset(%__MODULE__{} = domain, params \\ %{}) do
+    domain
+    |> cast(params, [:domain])
+  end
+
+  def get(id), do: Repo.get(__MODULE__, id)
+
+  def create(params) do
+    {:ok, domain} =
+      %__MODULE__{}
+      |> changeset(params)
+      |> Repo.insert()
+
+    domain
+  end
+
+  def update(params, id) do
+    {:ok, domain} =
+      get(id)
+      |> update_changeset(params)
+      |> Repo.update()
+
+    domain
+  end
+
+  def delete(id) do
+    get(id)
+    |> Repo.delete()
+  end
+end
diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index ce125d608..bb180517e 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -14,6 +14,7 @@ defmodule Pleroma.User do
   alias Pleroma.Config
   alias Pleroma.Conversation.Participation
   alias Pleroma.Delivery
+  alias Pleroma.Domain
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
   alias Pleroma.Emoji
   alias Pleroma.FollowingRelationship
@@ -157,6 +158,8 @@ defmodule Pleroma.User do
     field(:show_birthday, :boolean, default: false)
     field(:language, :string)
 
+    belongs_to(:domain, Domain)
+
     embeds_one(
       :notification_settings,
       Pleroma.User.NotificationSetting,
@@ -788,16 +791,18 @@ defmodule Pleroma.User do
       :accepts_chat_messages,
       :registration_reason,
       :birthday,
-      :language
+      :language,
+      :domain_id
     ])
     |> validate_required([:name, :nickname, :password, :password_confirmation])
     |> validate_confirmation(:password)
     |> unique_constraint(:email)
     |> validate_format(:email, @email_regex)
     |> validate_email_not_in_blacklisted_domain(:email)
-    |> unique_constraint(:nickname)
-    |> validate_not_restricted_nickname(:nickname)
     |> validate_format(:nickname, local_nickname_regex())
+    |> fix_nickname(Map.get(params, :domain_id), opts[:from_admin])
+    |> validate_not_restricted_nickname(:nickname)
+    |> unique_constraint(:nickname)
     |> validate_length(:bio, max: bio_limit)
     |> validate_length(:name, min: 1, max: name_limit)
     |> validate_length(:registration_reason, max: reason_limit)
@@ -811,6 +816,26 @@ defmodule Pleroma.User do
     |> put_private_key()
   end
 
+  defp fix_nickname(changeset, domain_id, from_admin) when is_binary(domain_id) do
+    with {:domain, domain} <- {:domain, Pleroma.Domain.get(domain_id)},
+         {:domain_allowed, true} <- {:domain_allowed, from_admin || domain.public} do
+      nickname = get_field(changeset, :nickname)
+
+      changeset
+      |> put_change(:nickname, nickname <> "@" <> domain.domain)
+      |> put_change(:domain, domain)
+    else
+      {:domain_allowed, false} ->
+        changeset
+        |> add_error(:domain, "not allowed to use this domain")
+
+      _ ->
+        changeset
+    end
+  end
+
+  defp fix_nickname(changeset, _, _), do: changeset
+
   def validate_not_restricted_nickname(changeset, field) do
     validate_change(changeset, field, fn _, value ->
       valid? =
@@ -871,7 +896,16 @@ defmodule Pleroma.User do
   end
 
   defp put_ap_id(changeset) do
-    ap_id = ap_id(%User{nickname: get_field(changeset, :nickname)})
+        nickname = get_field(changeset, :nickname)
+        ap_id = ap_id(%User{nickname: nickname})
+
+        ap_id =
+          if String.contains?(nickname, ".") do
+            ap_id <> ".json"
+          else
+            ap_id
+          end
+
     put_change(changeset, :ap_id, ap_id)
   end
 
@@ -1278,6 +1312,13 @@ defmodule Pleroma.User do
       restrict_to_local == :unauthenticated and match?(%User{}, opts[:for]) ->
         get_cached_by_nickname(nickname_or_id)
 
+      String.contains?(nickname_or_id, "@") ->
+        with %User{local: true} = user <- get_cached_by_nickname(nickname_or_id) do
+          user
+        else
+          _ -> nil
+        end
+
       true ->
         nil
     end
diff --git a/lib/pleroma/web/activity_pub/activity_pub_controller.ex b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
index 1357c379c..52668776f 100644
--- a/lib/pleroma/web/activity_pub/activity_pub_controller.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
@@ -66,7 +66,8 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
   end
 
   def user(conn, %{"nickname" => nickname}) do
-    with %User{local: true} = user <- User.get_cached_by_nickname(nickname) do
+    with %User{local: true} = user <-
+           nickname |> URI.decode() |> User.get_cached_by_nickname_or_id() do
       conn
       |> put_resp_content_type("application/activity+json")
       |> put_view(UserView)
diff --git a/lib/pleroma/web/activity_pub/views/user_view.ex b/lib/pleroma/web/activity_pub/views/user_view.ex
index f69fca075..1afa11e54 100644
--- a/lib/pleroma/web/activity_pub/views/user_view.ex
+++ b/lib/pleroma/web/activity_pub/views/user_view.ex
@@ -95,14 +95,21 @@ defmodule Pleroma.Web.ActivityPub.UserView do
         do: Date.to_iso8601(user.birthday),
         else: nil
 
+    ap_id =
+      if String.ends_with?(user.ap_id, ".json") do
+        String.slice(user.ap_id, 0..-6)
+      else
+        user.ap_id
+      end
+
     %{
       "id" => user.ap_id,
       "type" => user.actor_type,
-      "following" => "#{user.ap_id}/following",
-      "followers" => "#{user.ap_id}/followers",
-      "inbox" => "#{user.ap_id}/inbox",
-      "outbox" => "#{user.ap_id}/outbox",
-      "featured" => "#{user.ap_id}/collections/featured",
+      "following" => "#{ap_id}/following",
+      "followers" => "#{ap_id}/followers",
+      "inbox" => "#{ap_id}/inbox",
+      "outbox" => "#{ap_id}/outbox",
+      "featured" => "#{ap_id}/collections/featured",
       "preferredUsername" => user.nickname,
       "name" => user.name,
       "summary" => user.bio,
diff --git a/lib/pleroma/web/admin_api/controllers/domain_controller.ex b/lib/pleroma/web/admin_api/controllers/domain_controller.ex
new file mode 100644
index 000000000..46b039460
--- /dev/null
+++ b/lib/pleroma/web/admin_api/controllers/domain_controller.ex
@@ -0,0 +1,62 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2023 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.AdminAPI.DomainController do
+  use Pleroma.Web, :controller
+
+  alias Pleroma.Repo
+  alias Pleroma.Domain
+  alias Pleroma.Web.Plugs.OAuthScopesPlug
+
+  import Pleroma.Web.ControllerHelper,
+    only: [
+      json_response: 3
+    ]
+
+  plug(Pleroma.Web.ApiSpec.CastAndValidate)
+
+  plug(
+    OAuthScopesPlug,
+    %{scopes: ["admin:write"]}
+    when action in [:create, :update, :delete]
+  )
+
+  plug(OAuthScopesPlug, %{scopes: ["admin:read"]} when action == :index)
+
+  action_fallback(AdminAPI.FallbackController)
+
+  defdelegate open_api_operation(action), to: Pleroma.Web.ApiSpec.Admin.DomainOperation
+
+  def index(conn, _) do
+    domains =
+      Domain
+      |> Repo.all()
+
+    render(conn, "index.json", domains: domains)
+  end
+
+  def create(%{body_params: params} = conn, _) do
+    domain =
+      params
+      |> Domain.create()
+
+    render(conn, "show.json", domain: domain)
+  end
+
+  def update(%{body_params: params} = conn, %{id: id}) do
+    domain =
+      params
+      |> Domain.update(id)
+
+    render(conn, "show.json", domain: domain)
+  end
+
+  def delete(conn, %{id: id}) do
+    with {:ok, _} <- Domain.delete(id) do
+      json(conn, %{})
+    else
+      _ -> json_response(conn, :bad_request, "")
+    end
+  end
+end
diff --git a/lib/pleroma/web/admin_api/controllers/user_controller.ex b/lib/pleroma/web/admin_api/controllers/user_controller.ex
index 7b4ee46a4..e08831d5a 100644
--- a/lib/pleroma/web/admin_api/controllers/user_controller.ex
+++ b/lib/pleroma/web/admin_api/controllers/user_controller.ex
@@ -8,6 +8,7 @@ defmodule Pleroma.Web.AdminAPI.UserController do
   import Pleroma.Web.ControllerHelper,
     only: [fetch_integer_param: 3]
 
+  alias Pleroma.Domain
   alias Pleroma.ModerationLog
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.Builder
@@ -127,17 +128,20 @@ defmodule Pleroma.Web.AdminAPI.UserController do
   def create(%{assigns: %{user: admin}, body_params: %{users: users}} = conn, _) do
     changesets =
       users
-      |> Enum.map(fn %{nickname: nickname, email: email, password: password} ->
+      |> Enum.map(fn %{nickname: nickname, email: email, password: password, domain: domain} ->
+        domain = Domain.get(domain)
+
         user_data = %{
           nickname: nickname,
           name: nickname,
           email: email,
           password: password,
           password_confirmation: password,
-          bio: "."
+          bio: ".",
+          domain: domain
         }
 
-        User.register_changeset(%User{}, user_data, need_confirmation: false)
+        User.register_changeset(%User{}, user_data, need_confirmation: false, from_admin: true)
       end)
       |> Enum.reduce(Ecto.Multi.new(), fn changeset, multi ->
         Ecto.Multi.insert(multi, Ecto.UUID.generate(), changeset)
diff --git a/lib/pleroma/web/admin_api/views/domain_view.ex b/lib/pleroma/web/admin_api/views/domain_view.ex
new file mode 100644
index 000000000..0f91d4490
--- /dev/null
+++ b/lib/pleroma/web/admin_api/views/domain_view.ex
@@ -0,0 +1,21 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2023 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.AdminAPI.DomainView do
+  use Pleroma.Web, :view
+
+  alias Pleroma.Domain
+
+  def render("index.json", %{domains: domains}) do
+    render_many(domains, __MODULE__, "show.json")
+  end
+
+  def render("show.json", %{domain: %Domain{id: id, domain: domain, public: public}}) do
+    %{
+      id: id |> to_string(),
+      domain: domain,
+      public: public
+    }
+  end
+end
diff --git a/lib/pleroma/web/api_spec/operations/account_operation.ex b/lib/pleroma/web/api_spec/operations/account_operation.ex
index f2897a3a3..3855d1988 100644
--- a/lib/pleroma/web/api_spec/operations/account_operation.ex
+++ b/lib/pleroma/web/api_spec/operations/account_operation.ex
@@ -585,7 +585,8 @@ defmodule Pleroma.Web.ApiSpec.AccountOperation do
           type: :string,
           nullable: true,
           description: "User's preferred language for emails"
-        }
+        },
+        domain: %Schema{type: :string, nullable: true}
       },
       example: %{
         "username" => "cofe",
diff --git a/lib/pleroma/web/api_spec/operations/admin/domain_operation.ex b/lib/pleroma/web/api_spec/operations/admin/domain_operation.ex
new file mode 100644
index 000000000..d73c67b3d
--- /dev/null
+++ b/lib/pleroma/web/api_spec/operations/admin/domain_operation.ex
@@ -0,0 +1,111 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ApiSpec.Admin.DomainOperation do
+  alias OpenApiSpex.Operation
+  alias OpenApiSpex.Schema
+  alias Pleroma.Web.ApiSpec.Schemas.ApiError
+
+  import Pleroma.Web.ApiSpec.Helpers
+
+  def open_api_operation(action) do
+    operation = String.to_existing_atom("#{action}_operation")
+    apply(__MODULE__, operation, [])
+  end
+
+  def index_operation do
+    %Operation{
+      tags: ["Domain managment"],
+      summary: "Retrieve list of domains",
+      operationId: "AdminAPI.DomainController.index",
+      security: [%{"oAuth" => ["admin:read"]}],
+      responses: %{
+        200 =>
+          Operation.response("Response", "application/json", %Schema{
+            type: :array,
+            items: domain()
+          }),
+        403 => Operation.response("Forbidden", "application/json", ApiError)
+      }
+    }
+  end
+
+  def create_operation do
+    %Operation{
+      tags: ["Domain managment"],
+      summary: "Create new domain",
+      operationId: "AdminAPI.DomainController.create",
+      security: [%{"oAuth" => ["admin:write"]}],
+      parameters: admin_api_params(),
+      requestBody: request_body("Parameters", create_request(), required: true),
+      responses: %{
+        200 => Operation.response("Response", "application/json", domain()),
+        400 => Operation.response("Bad Request", "application/json", ApiError),
+        403 => Operation.response("Forbidden", "application/json", ApiError)
+      }
+    }
+  end
+
+  def update_operation do
+    %Operation{
+      tags: ["Domain managment"],
+      summary: "Modify existing domain",
+      operationId: "AdminAPI.DomainController.update",
+      security: [%{"oAuth" => ["admin:write"]}],
+      parameters: [Operation.parameter(:id, :path, :string, "Domain ID")],
+      requestBody: request_body("Parameters", update_request(), required: true),
+      responses: %{
+        200 => Operation.response("Response", "application/json", domain()),
+        400 => Operation.response("Bad Request", "application/json", ApiError),
+        403 => Operation.response("Forbidden", "application/json", ApiError)
+      }
+    }
+  end
+
+  def delete_operation do
+    %Operation{
+      tags: ["Domain managment"],
+      summary: "Delete domain",
+      operationId: "AdminAPI.DomainController.delete",
+      parameters: [Operation.parameter(:id, :path, :string, "Domain ID")],
+      security: [%{"oAuth" => ["admin:write"]}],
+      responses: %{
+        200 => empty_object_response(),
+        404 => Operation.response("Not Found", "application/json", ApiError),
+        403 => Operation.response("Forbidden", "application/json", ApiError)
+      }
+    }
+  end
+
+  defp create_request do
+    %Schema{
+      type: :object,
+      required: [:domain],
+      properties: %{
+        domain: %Schema{type: :string},
+        public: %Schema{type: :boolean, nullable: true}
+      }
+    }
+  end
+
+  defp update_request do
+    %Schema{
+      type: :object,
+      properties: %{
+        public: %Schema{type: :boolean, nullable: true}
+      }
+    }
+  end
+
+  defp domain do
+    %Schema{
+      type: :object,
+      properties: %{
+        id: %Schema{type: :integer},
+        domain: %Schema{type: :string},
+        public: %Schema{type: :boolean}
+      }
+    }
+  end
+end
diff --git a/lib/pleroma/web/api_spec/operations/admin/user_operation.ex b/lib/pleroma/web/api_spec/operations/admin/user_operation.ex
index a5179ac39..d2e76ff15 100644
--- a/lib/pleroma/web/api_spec/operations/admin/user_operation.ex
+++ b/lib/pleroma/web/api_spec/operations/admin/user_operation.ex
@@ -82,7 +82,8 @@ defmodule Pleroma.Web.ApiSpec.Admin.UserOperation do
                   properties: %{
                     nickname: %Schema{type: :string},
                     email: %Schema{type: :string},
-                    password: %Schema{type: :string}
+                    password: %Schema{type: :string},
+                    domain: %Schema{type: :string, nullable: true}
                   }
                 }
               }
diff --git a/lib/pleroma/web/mastodon_api/views/account_view.ex b/lib/pleroma/web/mastodon_api/views/account_view.ex
index cc3e3582f..c668ff1b7 100644
--- a/lib/pleroma/web/mastodon_api/views/account_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/account_view.ex
@@ -297,7 +297,8 @@ defmodule Pleroma.Web.MastodonAPI.AccountView do
         skip_thread_containment: user.skip_thread_containment,
         background_image: image_url(user.background) |> MediaProxy.url(),
         accepts_chat_messages: user.accepts_chat_messages,
-        favicon: favicon
+        favicon: favicon,
+        is_local: user.local
       }
     }
     |> maybe_put_role(user, opts[:for])
diff --git a/lib/pleroma/web/mastodon_api/views/instance_view.ex b/lib/pleroma/web/mastodon_api/views/instance_view.ex
index 1b01d7371..4ab4ccb74 100644
--- a/lib/pleroma/web/mastodon_api/views/instance_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/instance_view.ex
@@ -6,7 +6,10 @@ defmodule Pleroma.Web.MastodonAPI.InstanceView do
   use Pleroma.Web, :view
 
   alias Pleroma.Config
+  alias Pleroma.Domain
+  alias Pleroma.Repo
   alias Pleroma.Web.ActivityPub.MRF
+  alias Pleroma.Web.AdminAPI.DomainView
 
   @mastodon_api_level "2.7.2"
 
@@ -49,7 +52,8 @@ defmodule Pleroma.Web.MastodonAPI.InstanceView do
           fields_limits: fields_limits(),
           post_formats: Config.get([:instance, :allowed_post_formats]),
           birthday_required: Config.get([:instance, :birthday_required]),
-          birthday_min_age: Config.get([:instance, :birthday_min_age])
+          birthday_min_age: Config.get([:instance, :birthday_min_age]),
+          multitenancy: multitenancy()
         },
         stats: %{mau: Pleroma.User.active_user_count()},
         vapid_public_key: Keyword.get(Pleroma.Web.Push.vapid_config(), :public_key)
@@ -141,4 +145,21 @@ defmodule Pleroma.Web.MastodonAPI.InstanceView do
       value_length: Config.get([:instance, :account_field_value_length])
     }
   end
+
+  defp multitenancy do
+    enabled = Config.get([:multitenancy, :enabled])
+
+    if enabled do
+      domains =
+        [%Domain{id: "", domain: Pleroma.Web.WebFinger.domain(), public: true}] ++
+          Repo.all(Domain)
+
+      %{
+        enabled: true,
+        domains: DomainView.render("index.json", domains: domains)
+      }
+    else
+      nil
+    end
+  end
 end
diff --git a/lib/pleroma/web/router.ex b/lib/pleroma/web/router.ex
index 6b9e158a3..0dbdd2c90 100644
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@@ -286,6 +286,11 @@ defmodule Pleroma.Web.Router do
     post("/frontends/install", FrontendController, :install)
 
     post("/backups", AdminAPIController, :create_backup)
+
+    get("/domains", DomainController, :index)
+    post("/domains", DomainController, :create)
+    patch("/domains/:id", DomainController, :update)
+    delete("/domains/:id", DomainController, :delete)
   end
 
   # AdminAPI: admins and mods (staff) can perform these actions (if privileged by role)
diff --git a/lib/pleroma/web/twitter_api/twitter_api.ex b/lib/pleroma/web/twitter_api/twitter_api.ex
index ef2eb75f4..485a105e6 100644
--- a/lib/pleroma/web/twitter_api/twitter_api.ex
+++ b/lib/pleroma/web/twitter_api/twitter_api.ex
@@ -27,6 +27,7 @@ defmodule Pleroma.Web.TwitterAPI.TwitterAPI do
         :language,
         Pleroma.Web.Gettext.normalize_locale(params[:language]) || fallback_language
       )
+      |> Map.put(:domain_id, params[:domain])
 
     if Pleroma.Config.get([:instance, :registrations_open]) do
       create_user(params, opts)
diff --git a/lib/pleroma/web/web_finger.ex b/lib/pleroma/web/web_finger.ex
index f95dc2458..49c17e2c3 100644
--- a/lib/pleroma/web/web_finger.ex
+++ b/lib/pleroma/web/web_finger.ex
@@ -33,15 +33,13 @@ defmodule Pleroma.Web.WebFinger do
   def webfinger(resource, fmt) when fmt in ["XML", "JSON"] do
     host = Pleroma.Web.Endpoint.host()
 
-    regex =
-      if webfinger_domain = Pleroma.Config.get([__MODULE__, :domain]) do
-        ~r/(acct:)?(?<username>[a-z0-9A-Z_\.-]+)@(#{host}|#{webfinger_domain})/
-      else
-        ~r/(acct:)?(?<username>[a-z0-9A-Z_\.-]+)@#{host}/
-      end
+    regex = ~r/(acct:)?(?<username>[a-z0-9A-Z_\.-]+)@(?<domain>[a-z0-9A-Z_\.-]+)/
+    webfinger_domain = Pleroma.Config.get([__MODULE__, :domain])
 
-    with %{"username" => username} <- Regex.named_captures(regex, resource),
-         %User{} = user <- User.get_cached_by_nickname(username) do
+    with %{"username" => username, "domain" => domain} <- Regex.named_captures(regex, resource),
+         nickname <-
+           if(domain in [host, webfinger_domain], do: username, else: username <> "@" <> domain),
+         %User{local: true} = user <- User.get_cached_by_nickname(nickname) do
       {:ok, represent_user(user, fmt)}
     else
       _e ->
@@ -70,7 +68,7 @@ defmodule Pleroma.Web.WebFinger do
 
   def represent_user(user, "JSON") do
     %{
-      "subject" => "acct:#{user.nickname}@#{domain()}",
+      "subject" => get_subject(user),
       "aliases" => gather_aliases(user),
       "links" => gather_links(user)
     }
@@ -90,12 +88,20 @@ defmodule Pleroma.Web.WebFinger do
       :XRD,
       %{xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0"},
       [
-        {:Subject, "acct:#{user.nickname}@#{domain()}"}
+        {:Subject, get_subject(user)}
       ] ++ aliases ++ links
     }
     |> XmlBuilder.to_doc()
   end
 
+  defp get_subject(%User{nickname: nickname}) do
+    if String.contains?(nickname, "@") do
+      "acct:#{nickname}"
+    else
+      "acct:#{nickname}@#{domain()}"
+    end
+  end
+
   defp domain do
     Pleroma.Config.get([__MODULE__, :domain]) || Pleroma.Web.Endpoint.host()
   end
diff --git a/priv/repo/migrations/20230618190919_create_domains.exs b/priv/repo/migrations/20230618190919_create_domains.exs
new file mode 100644
index 000000000..a306c80ee
--- /dev/null
+++ b/priv/repo/migrations/20230618190919_create_domains.exs
@@ -0,0 +1,18 @@
+defmodule Pleroma.Repo.Migrations.CreateDomains do
+  use Ecto.Migration
+
+  def change do
+    create_if_not_exists table(:domains) do
+      add(:domain, :string)
+      add(:public, :boolean)
+
+      timestamps()
+    end
+
+    create_if_not_exists(unique_index(:domains, [:domain]))
+
+    alter table(:users) do
+      add(:domain_id, references(:domains))
+    end
+  end
+end