diff --git a/lib/onigumo/component.ex b/lib/onigumo/component.ex
new file mode 100644
index 0000000..f706af2
--- /dev/null
+++ b/lib/onigumo/component.ex
@@ -0,0 +1,4 @@
+defmodule Onigumo.Component do
+  @doc "Runs the component."
+  @callback main(root_path :: String.t()) :: :ok
+end
diff --git a/lib/onigumo/downloader.ex b/lib/onigumo/downloader.ex
index fa0606b..bf9ddf7 100644
--- a/lib/onigumo/downloader.ex
+++ b/lib/onigumo/downloader.ex
@@ -2,7 +2,9 @@ defmodule Onigumo.Downloader do
   @moduledoc """
   Web scraper
   """
+  @behaviour Onigumo.Component
 
+  @impl Onigumo.Component
   def main(root_path) do
     http_client().start()