diff --git a/lib/pleroma/web/activity_pub/object_validators/article_note_validator.ex b/lib/pleroma/web/activity_pub/object_validators/article_note_validator.ex
index b0388ef3b..5910f4060 100644
--- a/lib/pleroma/web/activity_pub/object_validators/article_note_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/article_note_validator.ex
@@ -9,6 +9,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.ArticleNoteValidator do
   alias Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonFixes
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
+  alias Pleroma.Web.ActivityPub.ObjectValidators.TagValidator
   alias Pleroma.Web.ActivityPub.Transmogrifier
 
   import Ecto.Changeset
@@ -22,8 +23,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.ArticleNoteValidator do
     field(:cc, ObjectValidators.Recipients, default: [])
     field(:bto, ObjectValidators.Recipients, default: [])
     field(:bcc, ObjectValidators.Recipients, default: [])
-    # TODO: Write type
-    field(:tag, {:array, :map}, default: [])
+    embeds_many(:tag, TagValidator)
     field(:type, :string)
 
     field(:name, :string)
@@ -90,8 +90,9 @@ def changeset(struct, data) do
     data = fix(data)
 
     struct
-    |> cast(data, __schema__(:fields) -- [:attachment])
+    |> cast(data, __schema__(:fields) -- [:attachment, :tag])
     |> cast_embed(:attachment)
+    |> cast_embed(:tag)
   end
 
   def validate_data(data_cng) do
diff --git a/lib/pleroma/web/activity_pub/object_validators/attachment_validator.ex b/lib/pleroma/web/activity_pub/object_validators/attachment_validator.ex
index 3175427ad..e7b3a3922 100644
--- a/lib/pleroma/web/activity_pub/object_validators/attachment_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/attachment_validator.ex
@@ -6,7 +6,6 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator do
   use Ecto.Schema
 
   alias Pleroma.EctoType.ActivityPub.ObjectValidators
-  alias Pleroma.Web.ActivityPub.ObjectValidators.UrlObjectValidator
 
   import Ecto.Changeset
 
diff --git a/lib/pleroma/web/activity_pub/object_validators/audio_video_validator.ex b/lib/pleroma/web/activity_pub/object_validators/audio_video_validator.ex
index 4a96fef52..a04c95f4b 100644
--- a/lib/pleroma/web/activity_pub/object_validators/audio_video_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/audio_video_validator.ex
@@ -10,6 +10,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.AudioVideoValidator do
   alias Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonFixes
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
+  alias Pleroma.Web.ActivityPub.ObjectValidators.TagValidator
   alias Pleroma.Web.ActivityPub.Transmogrifier
 
   import Ecto.Changeset
@@ -23,8 +24,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.AudioVideoValidator do
     field(:cc, ObjectValidators.Recipients, default: [])
     field(:bto, ObjectValidators.Recipients, default: [])
     field(:bcc, ObjectValidators.Recipients, default: [])
-    # TODO: Write type
-    field(:tag, {:array, :map}, default: [])
+    embeds_many(:tag, TagValidator)
     field(:type, :string)
 
     field(:name, :string)
@@ -132,8 +132,9 @@ def changeset(struct, data) do
     data = fix(data)
 
     struct
-    |> cast(data, __schema__(:fields) -- [:attachment])
+    |> cast(data, __schema__(:fields) -- [:attachment, :tag])
     |> cast_embed(:attachment)
+    |> cast_embed(:tag)
   end
 
   def validate_data(data_cng) do
diff --git a/lib/pleroma/web/activity_pub/object_validators/event_validator.ex b/lib/pleroma/web/activity_pub/object_validators/event_validator.ex
index 2e26726f8..0112a074d 100644
--- a/lib/pleroma/web/activity_pub/object_validators/event_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/event_validator.ex
@@ -9,6 +9,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.EventValidator do
   alias Pleroma.Web.ActivityPub.ObjectValidators.AttachmentValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonFixes
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
+  alias Pleroma.Web.ActivityPub.ObjectValidators.TagValidator
   alias Pleroma.Web.ActivityPub.Transmogrifier
 
   import Ecto.Changeset
@@ -23,8 +24,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.EventValidator do
     field(:cc, ObjectValidators.Recipients, default: [])
     field(:bto, ObjectValidators.Recipients, default: [])
     field(:bcc, ObjectValidators.Recipients, default: [])
-    # TODO: Write type
-    field(:tag, {:array, :map}, default: [])
+    embeds_many(:tag, TagValidator)
     field(:type, :string)
 
     field(:name, :string)
@@ -81,8 +81,9 @@ def changeset(struct, data) do
     data = fix(data)
 
     struct
-    |> cast(data, __schema__(:fields) -- [:attachment])
+    |> cast(data, __schema__(:fields) -- [:attachment, :tag])
     |> cast_embed(:attachment)
+    |> cast_embed(:tag)
   end
 
   def validate_data(data_cng) do
diff --git a/lib/pleroma/web/activity_pub/object_validators/question_validator.ex b/lib/pleroma/web/activity_pub/object_validators/question_validator.ex
index 6b746c997..7acb1e928 100644
--- a/lib/pleroma/web/activity_pub/object_validators/question_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/question_validator.ex
@@ -10,6 +10,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.QuestionValidator do
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonFixes
   alias Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
   alias Pleroma.Web.ActivityPub.ObjectValidators.QuestionOptionsValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.TagValidator
   alias Pleroma.Web.ActivityPub.Transmogrifier
 
   import Ecto.Changeset
@@ -24,8 +25,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.QuestionValidator do
     field(:cc, ObjectValidators.Recipients, default: [])
     field(:bto, ObjectValidators.Recipients, default: [])
     field(:bcc, ObjectValidators.Recipients, default: [])
-    # TODO: Write type
-    field(:tag, {:array, :map}, default: [])
+    embeds_many(:tag, TagValidator)
     field(:type, :string)
     field(:content, :string)
     field(:context, :string)
@@ -93,10 +93,11 @@ def changeset(struct, data) do
     data = fix(data)
 
     struct
-    |> cast(data, __schema__(:fields) -- [:anyOf, :oneOf, :attachment])
+    |> cast(data, __schema__(:fields) -- [:anyOf, :oneOf, :attachment, :tag])
     |> cast_embed(:attachment)
     |> cast_embed(:anyOf)
     |> cast_embed(:oneOf)
+    |> cast_embed(:tag)
   end
 
   def validate_data(data_cng) do
diff --git a/lib/pleroma/web/activity_pub/object_validators/tag_validator.ex b/lib/pleroma/web/activity_pub/object_validators/tag_validator.ex
new file mode 100644
index 000000000..751021585
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/object_validators/tag_validator.ex
@@ -0,0 +1,77 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.TagValidator do
+  use Ecto.Schema
+
+  alias Pleroma.EctoType.ActivityPub.ObjectValidators
+
+  import Ecto.Changeset
+
+  @primary_key false
+  embedded_schema do
+    # Common
+    field(:type, :string)
+    field(:name, :string)
+
+    # Mention, Hashtag
+    field(:href, ObjectValidators.Uri)
+
+    # Emoji
+    embeds_one :icon, IconObjectValidator, primary_key: false do
+      field(:type, :string)
+      field(:url, ObjectValidators.Uri)
+    end
+
+    field(:updated, ObjectValidators.DateTime)
+    field(:id, ObjectValidators.Uri)
+  end
+
+  def cast_and_validate(data) do
+    data
+    |> cast_data()
+  end
+
+  def cast_data(data) do
+    %__MODULE__{}
+    |> changeset(data)
+  end
+
+  def changeset(struct, %{"type" => "Mention"} = data) do
+    struct
+    |> cast(data, [:type, :name, :href])
+    |> validate_required([:type, :href])
+  end
+
+  def changeset(struct, %{"type" => "Hashtag", "name" => name} = data) do
+    name =
+      cond do
+        "#" <> name -> name
+        name -> name
+      end
+      |> String.downcase()
+
+    data = Map.put(data, "name", name)
+
+    struct
+    |> cast(data, [:type, :name, :href])
+    |> validate_required([:type, :name])
+  end
+
+  def changeset(struct, %{"type" => "Emoji"} = data) do
+    data = Map.put(data, "name", String.trim(data["name"], ":"))
+
+    struct
+    |> cast(data, [:type, :name, :updated, :id])
+    |> cast_embed(:icon, with: &icon_changeset/2)
+    |> validate_required([:type, :name, :icon])
+  end
+
+  def icon_changeset(struct, data) do
+    struct
+    |> cast(data, [:type, :url])
+    |> validate_inclusion(:type, ~w[Image])
+    |> validate_required([:type, :url])
+  end
+end