diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..1e582b0
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "mds-converter"]
+	path = mds-converter
+	url = git@github.com:markdown-docs/mds-converter.git
diff --git a/lib/backend/application.ex b/lib/backend/application.ex
index 5ef4648..a6571aa 100644
--- a/lib/backend/application.ex
+++ b/lib/backend/application.ex
@@ -19,7 +19,10 @@ defmodule Backend.Application do
       # Start to serve requests, typically the last entry
       BackendWeb.Endpoint,
       Backend.Files.FileRegistry,
-      Backend.Files.FileManager
+      Backend.Files.FileManager,
+      # Backend.Parsers.Pool
+      # Backend.Parsers.MdsParser
+      {Task.Supervisor, name: Backend.TaskSupervisor}
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html
diff --git a/lib/backend/files/files.ex b/lib/backend/files/files.ex
index 9e88272..34b2ae4 100644
--- a/lib/backend/files/files.ex
+++ b/lib/backend/files/files.ex
@@ -9,6 +9,10 @@ defmodule Backend.Files do
     Repo.get(File, id)
   end
 
+  def get_files() do
+    Repo.all(File)
+  end
+
   def create_file(attrs \\ %{}) do
     %File{}
     |> File.changeset(attrs)
diff --git a/lib/backend/parsers/mds_parser.ex b/lib/backend/parsers/mds_parser.ex
new file mode 100644
index 0000000..1151c40
--- /dev/null
+++ b/lib/backend/parsers/mds_parser.ex
@@ -0,0 +1,16 @@
+defmodule Backend.Parsers.MdsParser do
+  @moduledoc """
+  MdsParser used to invoke haskell parser
+  """
+
+  @parser_path Path.expand("mds-converter/runnable/parser", File.cwd!())
+
+  def parse(markdown) do
+    args = ["-c", markdown]
+
+    case System.cmd(@parser_path, args) do
+      {output, 0} -> {:ok, output}
+      {error, status} -> {:error, "Process failed with status #{status}: #{error}"}
+    end
+  end
+end
diff --git a/lib/backend_web/channels/file_channel.ex b/lib/backend_web/channels/file_channel.ex
new file mode 100644
index 0000000..344c0bc
--- /dev/null
+++ b/lib/backend_web/channels/file_channel.ex
@@ -0,0 +1,46 @@
+defmodule BackendWeb.FileChannel do
+  @moduledoc """
+  FileChannel used to interact with file's content
+  """
+
+  use Phoenix.Channel
+
+  alias Backend.Files
+  alias Backend.Files.FileManager
+  alias Backend.Parsers.MdsParser
+  alias BackendWeb.PreviewChannel
+
+  require Logger
+
+  def join("file:" <> file_id, _params, socket) do
+    case Files.get_file(file_id) do
+      nil -> {:error, %{reason: "File with id " <> file_id <> " does not exist"}}
+      _ -> {:ok, assign(socket, :file_id, file_id)}
+    end
+  end
+
+  def handle_in("edit", %{"content" => content}, socket) do
+    file_id = socket.assigns.file_id
+
+    Logger.debug("HANDLED edit INCOMING ON file:#{file_id}")
+    Logger.debug("  Parameters: #{inspect(%{"content" => content})}")
+
+    FileManager.update_file_content(file_id, content)
+    broadcast!(socket, "update", %{content: content})
+
+    Task.Supervisor.start_child(Backend.TaskSupervisor, fn ->
+      case MdsParser.parse(content) do
+        {:ok, html} ->
+          PreviewChannel.send_preview(file_id, html)
+          Logger.debug("SENT preview BACK ON preview:#{file_id}")
+          # Limit log size
+          Logger.debug("  HTML Content: #{String.slice(html, 0..100)}...")
+
+        {:error, reason} ->
+          Logger.error("Parser error: #{inspect(reason)}")
+      end
+    end)
+
+    {:noreply, socket}
+  end
+end
diff --git a/lib/backend_web/channels/preview_channel.ex b/lib/backend_web/channels/preview_channel.ex
new file mode 100644
index 0000000..3d5f76b
--- /dev/null
+++ b/lib/backend_web/channels/preview_channel.ex
@@ -0,0 +1,23 @@
+defmodule BackendWeb.PreviewChannel do
+  @moduledoc """
+  Websocket channel for each **converted** .mds file
+  """
+  use Phoenix.Channel
+
+  def join("preview:" <> file_id, _params, socket) do
+    # store process PID in ETS (Erlang Term Storage) to listen to messages in topic
+    Phoenix.PubSub.subscribe(Backend.PubSub, "preview:#{file_id}")
+    {:ok, assign(socket, :file_id, file_id)}
+  end
+
+  # Отправка готового превью
+  def send_preview(file_id, html) do
+    # find all subscribed to preview topic procs in ETS (Erlang Term Storage) and send them message
+    Phoenix.PubSub.broadcast(Backend.PubSub, "preview:#{file_id}", {:preview, html})
+  end
+
+  def handle_info({:preview, html}, socket) do
+    push(socket, "preview", %{html: html})
+    {:noreply, socket}
+  end
+end
diff --git a/lib/backend_web/channels/room_channel.ex b/lib/backend_web/channels/room_channel.ex
deleted file mode 100644
index 02861a8..0000000
--- a/lib/backend_web/channels/room_channel.ex
+++ /dev/null
@@ -1,27 +0,0 @@
-defmodule BackendWeb.FileChannel do
-  @moduledoc """
-  Websocket channel for each .mds file
-  """
-  alias Backend.Files
-  alias Backend.Files.FileManager
-  use Phoenix.Channel
-
-  def join("file:" <> file_id, _params, socket) do
-    case Files.get_file(file_id) do
-      nil -> {:error, %{reason: "File with id " <> file_id <> " does not exist"}}
-      _ -> {:ok, assign(socket, :file_id, file_id)}
-    end
-  end
-
-  def handle_in("edit", %{"content" => content}, socket) do
-    # Получаем file_id из socket.assigns
-    file_id = socket.assigns.file_id
-
-    # Вызываем FileManager для обновления содержимого файла
-    FileManager.update_file_content(file_id, content)
-
-    # Рассылаем обновления всем клиентам
-    broadcast!(socket, "update", %{content: content})
-    {:noreply, socket}
-  end
-end
diff --git a/lib/backend_web/channels/user_socket.ex b/lib/backend_web/channels/user_socket.ex
index 08151fe..0074892 100644
--- a/lib/backend_web/channels/user_socket.ex
+++ b/lib/backend_web/channels/user_socket.ex
@@ -2,8 +2,8 @@ defmodule BackendWeb.UserSocket do
   use Phoenix.Socket
 
   ## Каналы
-  # Это маршрут, на который будет подписан клиент
   channel "file:*", BackendWeb.FileChannel
+  channel "preview:*", BackendWeb.PreviewChannel
 
   # Здесь можно добавить авторизацию (опционально)
   def connect(_params, socket, _connect_info) do
diff --git a/lib/backend_web/controllers/file_controller.ex b/lib/backend_web/controllers/file_controller.ex
index 4d97003..6ed6704 100644
--- a/lib/backend_web/controllers/file_controller.ex
+++ b/lib/backend_web/controllers/file_controller.ex
@@ -18,6 +18,14 @@ defmodule BackendWeb.FileController do
     end
   end
 
+  def get_files(conn, _param) do
+    files = Files.get_files()
+
+    conn
+    |> put_status(200)
+    |> json(files)
+  end
+
   def create_file(conn, %{"name" => name}) do
     case Files.create_file(%{"name" => name, "content" => ""}) do
       {:ok, file} ->
diff --git a/lib/backend_web/endpoint.ex b/lib/backend_web/endpoint.ex
index 5728263..7a86dac 100644
--- a/lib/backend_web/endpoint.ex
+++ b/lib/backend_web/endpoint.ex
@@ -42,6 +42,7 @@ defmodule BackendWeb.Endpoint do
     param_key: "request_logger",
     cookie_key: "request_logger"
 
+  plug CORSPlug
   plug Plug.RequestId
   plug Plug.Telemetry, event_prefix: [:phoenix, :endpoint]
 
diff --git a/lib/backend_web/router.ex b/lib/backend_web/router.ex
index 70eb75f..0705423 100644
--- a/lib/backend_web/router.ex
+++ b/lib/backend_web/router.ex
@@ -20,6 +20,7 @@ defmodule BackendWeb.Router do
     get "/", PageController, :home
 
     get "/file/:id", FileController, :get_file
+    get "/file", FileController, :get_files
     post "/file", FileController, :create_file
     delete "/file/:id", FileController, :delete_file
   end
diff --git a/mds-converter b/mds-converter
new file mode 160000
index 0000000..d6a5414
--- /dev/null
+++ b/mds-converter
@@ -0,0 +1 @@
+Subproject commit d6a5414bd294df9fec3bdec454f5299f3579c6f6
diff --git a/mix.exs b/mix.exs
index a14294c..dca6ee1 100644
--- a/mix.exs
+++ b/mix.exs
@@ -68,7 +68,9 @@ defmodule Backend.MixProject do
       {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
       {:propcheck, "~> 1.4.1", only: [:test]},
       {:excoveralls, "~> 0.18", only: :test},
-      {:ecto_sqlite3, "~> 0.10.0"}
+      {:ecto_sqlite3, "~> 0.10.0"},
+      {:mock, "~> 0.3.8", only: :test},
+      {:cors_plug, "~> 3.0"}
     ]
   end
 
diff --git a/mix.lock b/mix.lock
index ea856cf..3cc520c 100644
--- a/mix.lock
+++ b/mix.lock
@@ -3,6 +3,7 @@
   "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
   "castore": {:hex, :castore, "1.0.10", "43bbeeac820f16c89f79721af1b3e092399b3a1ecc8df1a472738fd853574911", [:mix], [], "hexpm", "1b0b7ea14d889d9ea21202c43a4fa015eb913021cb535e8ed91946f4b77a8848"},
   "cc_precompiler": {:hex, :cc_precompiler, "0.1.10", "47c9c08d8869cf09b41da36538f62bc1abd3e19e41701c2cea2675b53c704258", [:mix], [{:elixir_make, "~> 0.7", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "f6e046254e53cd6b41c6bacd70ae728011aa82b2742a80d6e2214855c6e06b22"},
+  "cors_plug": {:hex, :cors_plug, "3.0.3", "7c3ac52b39624bc616db2e937c282f3f623f25f8d550068b6710e58d04a0e330", [:mix], [{:plug, "~> 1.13", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "3f2d759e8c272ed3835fab2ef11b46bddab8c1ab9528167bd463b6452edf830d"},
   "credo": {:hex, :credo, "1.7.10", "6e64fe59be8da5e30a1b96273b247b5cf1cc9e336b5fd66302a64b25749ad44d", [:mix], [{:bunt, "~> 0.2.1 or ~> 1.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2 or ~> 1.0", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "71fbc9a6b8be21d993deca85bf151df023a3097b01e09a2809d460348561d8cd"},
   "db_connection": {:hex, :db_connection, "2.7.0", "b99faa9291bb09892c7da373bb82cba59aefa9b36300f6145c5f201c7adf48ec", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "dcf08f31b2701f857dfc787fbad78223d61a32204f217f15e881dd93e4bdd3ff"},
   "decimal": {:hex, :decimal, "2.2.0", "df3d06bb9517e302b1bd265c1e7f16cda51547ad9d99892049340841f3e15836", [:mix], [], "hexpm", "af8daf87384b51b7e611fb1a1f2c4d4876b65ef968fa8bd3adf44cff401c7f21"},
@@ -23,8 +24,10 @@
   "hpax": {:hex, :hpax, "1.0.0", "28dcf54509fe2152a3d040e4e3df5b265dcb6cb532029ecbacf4ce52caea3fd2", [:mix], [], "hexpm", "7f1314731d711e2ca5fdc7fd361296593fc2542570b3105595bb0bc6d0fad601"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
   "libgraph": {:hex, :libgraph, "0.16.0", "3936f3eca6ef826e08880230f806bfea13193e49bf153f93edcf0239d4fd1d07", [:mix], [], "hexpm", "41ca92240e8a4138c30a7e06466acc709b0cbb795c643e9e17174a178982d6bf"},
+  "meck": {:hex, :meck, "0.9.2", "85ccbab053f1db86c7ca240e9fc718170ee5bda03810a6292b5306bf31bae5f5", [:rebar3], [], "hexpm", "81344f561357dc40a8344afa53767c32669153355b626ea9fcbc8da6b3045826"},
   "mime": {:hex, :mime, "2.0.6", "8f18486773d9b15f95f4f4f1e39b710045fa1de891fada4516559967276e4dc2", [:mix], [], "hexpm", "c9945363a6b26d747389aac3643f8e0e09d30499a138ad64fe8fd1d13d9b153e"},
   "mint": {:hex, :mint, "1.6.2", "af6d97a4051eee4f05b5500671d47c3a67dac7386045d87a904126fd4bbcea2e", [:mix], [{:castore, "~> 0.1.0 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}, {:hpax, "~> 0.1.1 or ~> 0.2.0 or ~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}], "hexpm", "5ee441dffc1892f1ae59127f74afe8fd82fda6587794278d924e4d90ea3d63f9"},
+  "mock": {:hex, :mock, "0.3.8", "7046a306b71db2488ef54395eeb74df0a7f335a7caca4a3d3875d1fc81c884dd", [:mix], [{:meck, "~> 0.9.2", [hex: :meck, repo: "hexpm", optional: false]}], "hexpm", "7fa82364c97617d79bb7d15571193fc0c4fe5afd0c932cef09426b3ee6fe2022"},
   "nimble_options": {:hex, :nimble_options, "1.1.1", "e3a492d54d85fc3fd7c5baf411d9d2852922f66e69476317787a7b2bb000a61b", [:mix], [], "hexpm", "821b2470ca9442c4b6984882fe9bb0389371b8ddec4d45a9504f00a66f650b44"},
   "nimble_pool": {:hex, :nimble_pool, "1.1.0", "bf9c29fbdcba3564a8b800d1eeb5a3c58f36e1e11d7b7fb2e084a643f645f06b", [:mix], [], "hexpm", "af2e4e6b34197db81f7aad230c1118eac993acc0dae6bc83bac0126d4ae0813a"},
   "phoenix": {:hex, :phoenix, "1.7.14", "a7d0b3f1bc95987044ddada111e77bd7f75646a08518942c72a8440278ae7825", [:mix], [{:castore, ">= 0.0.0", [hex: :castore, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 2.1", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:phoenix_template, "~> 1.0", [hex: :phoenix_template, repo: "hexpm", optional: false]}, {:phoenix_view, "~> 2.0", [hex: :phoenix_view, repo: "hexpm", optional: true]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 2.7", [hex: :plug_cowboy, repo: "hexpm", optional: true]}, {:plug_crypto, "~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:websock_adapter, "~> 0.5.3", [hex: :websock_adapter, repo: "hexpm", optional: false]}], "hexpm", "c7859bc56cc5dfef19ecfc240775dae358cbaa530231118a9e014df392ace61a"},
@@ -37,6 +40,7 @@
   "phoenix_template": {:hex, :phoenix_template, "1.0.4", "e2092c132f3b5e5b2d49c96695342eb36d0ed514c5b252a77048d5969330d639", [:mix], [{:phoenix_html, "~> 2.14.2 or ~> 3.0 or ~> 4.0", [hex: :phoenix_html, repo: "hexpm", optional: true]}], "hexpm", "2c0c81f0e5c6753faf5cca2f229c9709919aba34fab866d3bc05060c9c444206"},
   "plug": {:hex, :plug, "1.16.1", "40c74619c12f82736d2214557dedec2e9762029b2438d6d175c5074c933edc9d", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "a13ff6b9006b03d7e33874945b2755253841b238c34071ed85b0e86057f8cddc"},
   "plug_crypto": {:hex, :plug_crypto, "2.1.0", "f44309c2b06d249c27c8d3f65cfe08158ade08418cf540fd4f72d4d6863abb7b", [:mix], [], "hexpm", "131216a4b030b8f8ce0f26038bc4421ae60e4bb95c5cf5395e1421437824c4fa"},
+  "poolboy": {:hex, :poolboy, "1.5.2", "392b007a1693a64540cead79830443abf5762f5d30cf50bc95cb2c1aaafa006b", [:rebar3], [], "hexpm", "dad79704ce5440f3d5a3681c8590b9dc25d1a561e8f5a9c995281012860901e3"},
   "postgrex": {:hex, :postgrex, "0.19.3", "a0bda6e3bc75ec07fca5b0a89bffd242ca209a4822a9533e7d3e84ee80707e19", [:mix], [{:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "d31c28053655b78f47f948c85bb1cf86a9c1f8ead346ba1aa0d0df017fa05b61"},
   "propcheck": {:hex, :propcheck, "1.4.1", "c12908dbe6f572032928548089b34ff9d40672d5d70f1562e3a9e9058d226cc9", [:mix], [{:libgraph, "~> 0.13", [hex: :libgraph, repo: "hexpm", optional: false]}, {:proper, "~> 1.4", [hex: :proper, repo: "hexpm", optional: false]}], "hexpm", "e1b088f574785c3c7e864da16f39082d5599b3aaf89086d3f9be6adb54464b19"},
   "proper": {:hex, :proper, "1.4.0", "89a44b8c39d28bb9b4be8e4d715d534905b325470f2e0ec5e004d12484a79434", [:rebar3], [], "hexpm", "18285842185bd33efbda97d134a5cb5a0884384db36119fee0e3cfa488568cbb"},
diff --git a/priv/repo/migrations/20241129212656_add_file.exs b/priv/repo/migrations/20241129212656_add_file.exs
index ec46f1c..d809bf3 100644
--- a/priv/repo/migrations/20241129212656_add_file.exs
+++ b/priv/repo/migrations/20241129212656_add_file.exs
@@ -4,7 +4,7 @@ defmodule Backend.Repo.Migrations.AddFile do
   def change do
     create table(:files) do
       add :name, :string, null: false
-      add :content, :string
+      add :content, :string, size: 10000
     end
   end
 end
diff --git a/test/backend/mds_parser_test.exs b/test/backend/mds_parser_test.exs
new file mode 100644
index 0000000..8892689
--- /dev/null
+++ b/test/backend/mds_parser_test.exs
@@ -0,0 +1,38 @@
+defmodule Backend.Parsers.MdsParserTest do
+  use ExUnit.Case, async: true
+
+  alias Backend.Parsers.MdsParser
+
+  @parser_path Path.expand("mds-converter/runnable/parser", File.cwd!())
+
+  setup do
+    # Проверяем, существует ли парсер
+    if File.exists?(@parser_path) do
+      :ok
+    else
+      {:error, "Parser executable not found at #{@parser_path}"}
+    end
+  end
+
+  test "parses valid content" do
+    content = "# Test\n\nSome **bold** text"
+    assert {:ok, html} = MdsParser.parse(content)
+
+    assert html =~
+             "<!DOCTYPE html>\n<html>\n<head>\n<meta charset=\"UTF-8\">\n</head>\n<body>\n<h1 id=\"0cbc6611f5540bd0809a388dc95a615b\">Test</h1>\n<p>Some <strong>bold</strong> text</p>\n\n</body>\n</html>\n"
+  end
+
+  test "handles invalid content gracefully" do
+    content = ""
+    assert {:ok, html} = MdsParser.parse(content)
+
+    # Даже пустой контент должен возвращать корректный HTML
+    assert html =~ "<body>"
+  end
+
+  test "handles parser errors" do
+    # Очень длинный ввод для потенциальной ошибки
+    content = :binary.copy("a", 1_000_000)
+    assert {:error, _} = MdsParser.parse(content)
+  end
+end
diff --git a/test/test_helper.exs b/test/test_helper.exs
index 9cb37c0..06ec5e7 100644
--- a/test/test_helper.exs
+++ b/test/test_helper.exs
@@ -5,4 +5,7 @@ Mix.Task.run("ecto.create", ["--quiet"])
 Mix.Task.run("ecto.migrate", ["--quiet"])
 
 ExUnit.start()
+# Code.require_file("support/channel_case.ex", __DIR__)
+Code.require_file("support/data_case.ex", __DIR__)
+Code.require_file("support/conn_case.ex", __DIR__)
 Ecto.Adapters.SQL.Sandbox.mode(Backend.Repo, :manual)