diff --git a/lib/pleroma/web/activity_pub/activity_pub_controller.ex b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
index 60b289f08..56af34c67 100644
--- a/lib/pleroma/web/activity_pub/activity_pub_controller.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
@@ -92,14 +92,15 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
     with ap_id <- Endpoint.url() <> conn.request_path,
          %Object{} = object <- Object.get_cached_by_ap_id(ap_id),
          user <- Map.get(assigns, :user, nil),
-         {_, true} <- {:visible?, Visibility.visible_for_user?(object, user)} do
+         {_, true} <- {:visible?, Visibility.visible_for_user?(object, user)},
+         host <- maybe_get_host(Map.get(assigns, :actor_id, nil)) do
       conn
       |> maybe_skip_cache(user)
       |> assign(:tracking_fun_data, object.id)
       |> set_cache_ttl_for(object)
       |> put_resp_content_type("application/activity+json")
       |> put_view(ObjectView)
-      |> render("object.json", object: object)
+      |> render("object.json", object: object, host: host)
     else
       {:visible?, false} -> {:error, :not_found}
       nil -> {:error, :not_found}
@@ -121,14 +122,15 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
          %Activity{} = activity <- Activity.normalize(ap_id),
          {_, true} <- {:local?, activity.local},
          user <- Map.get(assigns, :user, nil),
-         {_, true} <- {:visible?, Visibility.visible_for_user?(activity, user)} do
+         {_, true} <- {:visible?, Visibility.visible_for_user?(activity, user)},
+         host <- maybe_get_host(Map.get(assigns, :actor_id, nil)) do
       conn
       |> maybe_skip_cache(user)
       |> maybe_set_tracking_data(activity)
       |> set_cache_ttl_for(activity)
       |> put_resp_content_type("application/activity+json")
       |> put_view(ObjectView)
-      |> render("object.json", object: activity)
+      |> render("object.json", object: activity, host: host)
     else
       {:visible?, false} -> {:error, :not_found}
       {:local?, false} -> {:error, :not_found}
@@ -136,6 +138,14 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
     end
   end
 
+  defp maybe_get_host(actor_id) when is_binary(actor_id) do
+    %{host: host} = URI.parse(actor_id)
+
+    host
+  end
+
+  defp maybe_get_host(_), do: nil
+
   defp maybe_set_tracking_data(conn, %Activity{data: %{"type" => "Create"}} = activity) do
     object_id = Object.normalize(activity, fetch: false).id
     assign(conn, :tracking_fun_data, object_id)
diff --git a/lib/pleroma/web/activity_pub/publisher.ex b/lib/pleroma/web/activity_pub/publisher.ex
index 0de3a0d43..3fd0d1316 100644
--- a/lib/pleroma/web/activity_pub/publisher.ex
+++ b/lib/pleroma/web/activity_pub/publisher.ex
@@ -89,9 +89,9 @@ defmodule Pleroma.Web.ActivityPub.Publisher do
 
     ap_id = activity.data["id"]
     Logger.debug("Federating #{ap_id} to #{inbox}")
-    uri = %{path: path} = URI.parse(inbox)
+    uri = %{host: host, path: path} = URI.parse(inbox)
 
-    {:ok, data} = Transmogrifier.prepare_outgoing(activity.data)
+    {:ok, data} = Transmogrifier.prepare_outgoing(activity.data, host)
 
     cc = Map.get(params, :cc, [])
 
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 69e6a63a7..44e221fd7 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -723,7 +723,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   defp set_voters_count(obj), do: obj
 
   # Prepares the object of an outgoing create activity.
-  def prepare_object(object) do
+  def prepare_object(object, host \\ nil) do
     object
     |> add_hashtags
     |> add_mention_tags
@@ -738,15 +738,21 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     |> strip_internal_fields
     |> strip_internal_tags
     |> set_type
-    |> maybe_process_history
+    |> maybe_process_history(host)
+    |> patch_object(host)
   end
 
-  defp maybe_process_history(%{"formerRepresentations" => %{"orderedItems" => history}} = object) do
+  defp maybe_process_history(object, host)
+
+  defp maybe_process_history(
+         %{"formerRepresentations" => %{"orderedItems" => history}} = object,
+         host
+       ) do
     processed_history =
       Enum.map(
         history,
         fn
-          item when is_map(item) -> prepare_object(item)
+          item when is_map(item) -> prepare_object(item, host)
           item -> item
         end
       )
@@ -754,7 +760,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     put_in(object, ["formerRepresentations", "orderedItems"], processed_history)
   end
 
-  defp maybe_process_history(object) do
+  defp maybe_process_history(object, _host) do
     object
   end
 
@@ -763,7 +769,9 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   #  internal -> Mastodon
   #  """
 
-  def prepare_outgoing(%{"type" => activity_type, "object" => object_id} = data)
+  def prepare_outgoing(data, host \\ nil)
+
+  def prepare_outgoing(%{"type" => activity_type, "object" => object_id} = data, host)
       when activity_type in ["Create", "Listen"] do
     object =
       object_id
@@ -772,32 +780,38 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
     data =
       data
-      |> Map.put("object", prepare_object(object))
+      |> Map.put("object", prepare_object(object, host))
       |> Map.merge(Utils.make_json_ld_header(object))
       |> Map.delete("bcc")
 
     {:ok, data}
   end
 
-  def prepare_outgoing(%{"type" => "Update", "object" => %{"type" => objtype} = object} = data)
+  def prepare_outgoing(
+        %{"type" => "Update", "object" => %{"type" => objtype} = object} = data,
+        host
+      )
       when objtype in Pleroma.Constants.updatable_object_types() do
     data =
       data
-      |> Map.put("object", prepare_object(object))
+      |> Map.put("object", prepare_object(object, host))
       |> Map.merge(Utils.make_json_ld_header(object))
       |> Map.delete("bcc")
 
     {:ok, data}
   end
 
-  def prepare_outgoing(%{"type" => "Announce", "actor" => ap_id, "object" => object_id} = data) do
+  def prepare_outgoing(
+        %{"type" => "Announce", "actor" => ap_id, "object" => object_id} = data,
+        host
+      ) do
     object =
       object_id
       |> Object.normalize(fetch: false)
 
     data =
       if Visibility.private?(object) && object.data["actor"] == ap_id do
-        data |> Map.put("object", object |> Map.get(:data) |> prepare_object)
+        data |> Map.put("object", object |> Map.get(:data) |> prepare_object(host))
       else
         data |> maybe_fix_object_url
       end
@@ -813,7 +827,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
   # Mastodon Accept/Reject requires a non-normalized object containing the actor URIs,
   # because of course it does.
-  def prepare_outgoing(%{"type" => "Accept"} = data) do
+  def prepare_outgoing(%{"type" => "Accept"} = data, _host) do
     with follow_activity <- Activity.normalize(data["object"]) do
       object = %{
         "actor" => follow_activity.actor,
@@ -831,7 +845,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
-  def prepare_outgoing(%{"type" => "Reject"} = data) do
+  def prepare_outgoing(%{"type" => "Reject"} = data, _host) do
     with follow_activity <- Activity.normalize(data["object"]) do
       object = %{
         "actor" => follow_activity.actor,
@@ -849,7 +863,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
-  def prepare_outgoing(%{"type" => _type} = data) do
+  def prepare_outgoing(%{"type" => _type} = data, _host) do
     data =
       data
       |> strip_internal_fields
@@ -1000,4 +1014,39 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   def maybe_fix_user_url(data), do: data
 
   def maybe_fix_user_object(data), do: maybe_fix_user_url(data)
+
+  defp patch_object(nil, _host), do: nil
+
+  defp patch_object(object, nil), do: object
+
+  defp patch_object(object, host) do
+    object
+    |> update_if_exists("source", &patch_object(&1, host))
+    |> update_if_exists("content", &replace_instance_host(&1, host))
+    |> patch_content_map(host)
+  end
+
+  defp patch_content_map(%{"contentMap" => %{} = content_map}, host) do
+    content_map
+    |> Enum.map(fn {key, value} -> {key, replace_instance_host(value, host)} end)
+    |> Map.new()
+  end
+
+  defp patch_content_map(content_map, _host), do: content_map
+
+  defp replace_instance_host(content, host) when is_binary(content) and is_binary(host) do
+    content
+    |> String.replace("$INSTANCE$host$", host)
+  end
+
+  defp replace_instance_host(content, _), do: content
+
+  defp update_if_exists(map, key, func) do
+    if Map.has_key?(map, key) do
+      value = Map.get(map, key)
+      Map.put(map, key, func.(value))
+    else
+      map
+    end
+  end
 end
diff --git a/lib/pleroma/web/activity_pub/views/object_view.ex b/lib/pleroma/web/activity_pub/views/object_view.ex
index 13b5b2542..9b716a3f3 100644
--- a/lib/pleroma/web/activity_pub/views/object_view.ex
+++ b/lib/pleroma/web/activity_pub/views/object_view.ex
@@ -8,31 +8,34 @@ defmodule Pleroma.Web.ActivityPub.ObjectView do
   alias Pleroma.Object
   alias Pleroma.Web.ActivityPub.Transmogrifier
 
-  def render("object.json", %{object: %Object{} = object}) do
+  def render("object.json", %{object: %Object{} = object, host: host}) do
     base = Pleroma.Web.ActivityPub.Utils.make_json_ld_header(object.data)
 
-    additional = Transmogrifier.prepare_object(object.data)
+    additional = Transmogrifier.prepare_object(object.data, host)
     Map.merge(base, additional)
   end
 
-  def render("object.json", %{object: %Activity{data: %{"type" => activity_type}} = activity})
+  def render("object.json", %{
+        object: %Activity{data: %{"type" => activity_type}} = activity,
+        host: host
+      })
       when activity_type in ["Create", "Listen"] do
     base = Pleroma.Web.ActivityPub.Utils.make_json_ld_header(activity.data)
     object = Object.normalize(activity, fetch: false)
 
     additional =
       Transmogrifier.prepare_object(activity.data)
-      |> Map.put("object", Transmogrifier.prepare_object(object.data))
+      |> Map.put("object", Transmogrifier.prepare_object(object.data, host))
 
     Map.merge(base, additional)
   end
 
-  def render("object.json", %{object: %Activity{} = activity}) do
+  def render("object.json", %{object: %Activity{} = activity, host: host}) do
     base = Pleroma.Web.ActivityPub.Utils.make_json_ld_header(activity.data)
     object_id = Object.normalize(activity, id_only: true)
 
     additional =
-      Transmogrifier.prepare_object(activity.data)
+      Transmogrifier.prepare_object(activity.data, host)
       |> Map.put("object", object_id)
 
     Map.merge(base, additional)
diff --git a/lib/pleroma/web/activity_pub/views/user_view.ex b/lib/pleroma/web/activity_pub/views/user_view.ex
index 1261ba4cf..fbc09cd0d 100644
--- a/lib/pleroma/web/activity_pub/views/user_view.ex
+++ b/lib/pleroma/web/activity_pub/views/user_view.ex
@@ -269,7 +269,7 @@ defmodule Pleroma.Web.ActivityPub.UserView do
       pinned_objects
       |> Enum.sort_by(fn {_, pinned_at} -> pinned_at end, &>=/2)
       |> Enum.map(fn {id, _} ->
-        ObjectView.render("object.json", %{object: Object.get_cached_by_ap_id(id)})
+        ObjectView.render("object.json", %{object: Object.get_cached_by_ap_id(id), host: nil})
       end)
 
     %{