diff --git a/lib/simple_blog/converter/page.ex b/lib/simple_blog/converter/page.ex
index 0cd7dd0..3e5b4dc 100644
--- a/lib/simple_blog/converter/page.ex
+++ b/lib/simple_blog/converter/page.ex
@@ -3,6 +3,7 @@ defmodule SimpleBlog.Converter.Page do
   Module responsible for convert pages from eex to html
   """
 
+  $ type parsed() = {{:ok, string()}}
   @doc """
   Convert eex file to html
 
@@ -16,6 +17,7 @@ defmodule SimpleBlog.Converter.Page do
       iex> SimpleBlog.Converter.Page.eex_to_html({:ok, "<%= post.title %>"}, post)
       "post 1"
   """
+  $ (parsed(),[posts]) -> string() when posts: SimpleBlog.Post.t()
   def eex_to_html({:ok, body}, posts) when is_list(posts) do
     quoted = EEx.compile_string(body)
 
@@ -24,6 +26,7 @@ defmodule SimpleBlog.Converter.Page do
     end
   end
 
+  $ (parsed(), SimpleBlog.Post.t()) -> string()
   def eex_to_html({:ok, body}, post) do
     quoted = EEx.compile_string(body)
 
diff --git a/lib/simple_blog/converter/posts.ex b/lib/simple_blog/converter/posts.ex
index 645e8f6..659ae25 100644
--- a/lib/simple_blog/converter/posts.ex
+++ b/lib/simple_blog/converter/posts.ex
@@ -19,8 +19,10 @@ defmodule SimpleBlog.Converter.Posts do
       iex> SimpleBlog.Converter.Posts.markdown_to_html([])
       []
   """
+  $ list() -> list()
   def markdown_to_html([]), do: []
 
+  $ [files] -> string() when files: string()
   def markdown_to_html(files) when is_list(files) do
     html =
       for file <- files do
@@ -31,6 +33,7 @@ defmodule SimpleBlog.Converter.Posts do
     html
   end
 
+  $ string() -> string()
   def markdown_to_html(file) do
     {:ok, html_doc, []} = Earmark.as_html(file)
     html_doc
diff --git a/lib/simple_blog/post.ex b/lib/simple_blog/post.ex
index 040cb53..5d05e11 100644
--- a/lib/simple_blog/post.ex
+++ b/lib/simple_blog/post.ex
@@ -15,6 +15,7 @@ defmodule SimpleBlog.Post do
       iex> SimpleBlog.Post.generate_filename(%SimpleBlog.Post{ title: "My first blog post", date: ~D[2023-10-04]})
       "2023-10-04-my-first-blog-post.md"
   """
+  $ SimpleBlog.Post.t() -> string()
   def generate_filename(%SimpleBlog.Post{title: title, date: date}) do
     normalized_title =
       title
@@ -36,6 +37,7 @@ defmodule SimpleBlog.Post do
       iex> SimpleBlog.Post.parse(body)
       %SimpleBlog.Post{body: body, title: "Dev onboarding", date: "2023-10-25", filename: "2023-10-25-dev-onboarding.md"}
   """
+  $ string() -> SimpleBlog.Post.t()
   def parse(body) do
     [_, filename_line, title_line, date_line | _] = String.split(body, "\n")
 
@@ -54,6 +56,7 @@ defmodule SimpleBlog.Post do
       iex> SimpleBlog.Post.generate_html_dir(%SimpleBlog.Post{date: "2023-10-04"}, "output")
       "output/2023/10/04/"
   """
+  $ (SimpleBlog.Post.t(), string()) -> string()
   def generate_html_dir(%SimpleBlog.Post{date: date}, base_dir) do
     [year, month, day] = String.split(date, "-")
     base_dir <> "/" <> year <> "/" <> month <> "/" <> day <> "/"
@@ -67,6 +70,7 @@ defmodule SimpleBlog.Post do
       iex> SimpleBlog.Post.generate_html_filename(%SimpleBlog.Post{title: "doctests with elixir"})
       "doctests-with-elixir.html"
   """
+  $ SimpleBlog.Post.t() -> string()
   def generate_html_filename(%SimpleBlog.Post{title: title}) do
     title
     |> String.replace(" ", "-")
diff --git a/lib/simple_blog/reader/posts.ex b/lib/simple_blog/reader/posts.ex
index 0181dca..d5b7a06 100644
--- a/lib/simple_blog/reader/posts.ex
+++ b/lib/simple_blog/reader/posts.ex
@@ -11,6 +11,7 @@ defmodule SimpleBlog.Reader.Posts do
       iex> SimpleBlog.Reader.Posts.read_from_dir("blog")
       ["## post title 1", "## post title 2"]
   """
+  $ string() -> list()
   def read_from_dir(root_directory) do
     posts_directory = root_directory <> "/_posts/"
 
@@ -28,6 +29,7 @@ defmodule SimpleBlog.Reader.Posts do
       iex> SimpleBlog.Reader.Posts.read_post("blog", "2023-10-25-metaprogramming-in-ruby.md")
       "### Metaprogramming in ruby"
   """
+  $ (string(), string()) -> string()
   def read_post(root_directory, post) do
     posts_directory = root_directory <> "/_posts/"
     post_path = posts_directory <> post
@@ -40,6 +42,7 @@ defmodule SimpleBlog.Reader.Posts do
 
   defp pipeline(_posts_directory, []), do: []
 
+  $ (string(), list()) -> list()
   defp pipeline(posts_directory, files) when is_list(files) do
     files
     |> Enum.map(fn file -> full_path(file, posts_directory) end)
diff --git a/lib/simple_blog/rewrite_html/back_link.ex b/lib/simple_blog/rewrite_html/back_link.ex
index 2da4036..b865c18 100644
--- a/lib/simple_blog/rewrite_html/back_link.ex
+++ b/lib/simple_blog/rewrite_html/back_link.ex
@@ -14,6 +14,7 @@ defmodule SimpleBlog.RewriteHTML.BackLink do
       iex> SimpleBlog.RewriteHTML.BackLink.rewrite(link)
       ~s(<a href="../../../../index.html" class="back-link">Back</a>)
   """
+  $ string() -> string()
   def rewrite(html) do
     {:ok, document} = Floki.parse_document(html)
 
diff --git a/lib/simple_blog/rewrite_html/image.ex b/lib/simple_blog/rewrite_html/image.ex
index f7ecfb9..051c4bf 100644
--- a/lib/simple_blog/rewrite_html/image.ex
+++ b/lib/simple_blog/rewrite_html/image.ex
@@ -1,6 +1,7 @@
 defmodule SimpleBlog.RewriteHTML.Image do
   require Floki
 
+  $ string() -> string()
   def rewrite(html, path) do
     {:ok, document} = Floki.parse_document(html)
 
diff --git a/lib/simple_blog/rewrite_html/posts_link.ex b/lib/simple_blog/rewrite_html/posts_link.ex
index 775c167..5bb44bd 100644
--- a/lib/simple_blog/rewrite_html/posts_link.ex
+++ b/lib/simple_blog/rewrite_html/posts_link.ex
@@ -1,6 +1,7 @@
 defmodule SimpleBlog.RewriteHTML.PostsLink do
   require Floki
 
+  $ string() -> string()
   def rewrite(html) do
     {:ok, document} = Floki.parse_document(html)
 
@@ -11,6 +12,7 @@ defmodule SimpleBlog.RewriteHTML.PostsLink do
     |> Floki.raw_html()
   end
 
+  $ string() -> string()
   defp filename(x) do
     href =
       String.split(x, "?post=")
diff --git a/lib/simple_blog/rewrite_html/stylesheet.ex b/lib/simple_blog/rewrite_html/stylesheet.ex
index 5b617ca..a0299f9 100644
--- a/lib/simple_blog/rewrite_html/stylesheet.ex
+++ b/lib/simple_blog/rewrite_html/stylesheet.ex
@@ -1,6 +1,7 @@
 defmodule SimpleBlog.RewriteHTML.Stylesheet do
   require Floki
 
+  $ (string(), string()) -> string()
   def rewrite(html, path) do
     {:ok, document} = Floki.parse_document(html)
 
diff --git a/lib/simple_blog/server.ex b/lib/simple_blog/server.ex
index 7a6b1a3..4d35fc3 100644
--- a/lib/simple_blog/server.ex
+++ b/lib/simple_blog/server.ex
@@ -14,6 +14,18 @@ defmodule SimpleBlog.Server do
   @doc """
   Initializes server passing initial params
   """
+
+  $type opts() ::
+  string()
+  | tuple()
+  | atom()
+  | integer()
+  | float()
+  | [opts()]
+  | %{optional(opts()) => opts()}
+  | MapSet.t()
+
+  $ opts() -> opts()
   def init(_options) do
     Logger.info("Initializing server ...")
   end
@@ -21,6 +33,8 @@ defmodule SimpleBlog.Server do
   @doc """
   Handle HTTP requests.
   """
+  # Verificar se é assim mesmo
+  $ (Plug.Conn.t(), opts()) -> Plug.Conn.t()
   def call(%Plug.Conn{request_path: "/posts/", query_string: query_string} = conn, _opts) do
     postname =
       query_string
@@ -42,6 +56,7 @@ defmodule SimpleBlog.Server do
     |> send_resp(200, result)
   end
 
+  $ (Plug.Conn.t(), opts()) -> Plug.Conn.t()
   def call(%Plug.Conn{request_path: "/"} = conn, _opts) do
     posts =
       "blog"
@@ -58,6 +73,7 @@ defmodule SimpleBlog.Server do
     |> send_resp(200, result)
   end
 
+  $ (Plug.Conn.t(), opts()) -> Plug.Conn.t()
   def call(
         %Plug.Conn{request_path: _request_path, req_headers: [{"accept", accept} | _]} = conn,
         _opts
@@ -68,6 +84,7 @@ defmodule SimpleBlog.Server do
     end
   end
 
+  $ (Plug.Conn.t(), string()) -> Plug.Conn.t()
   defp asset_pipeline(%Plug.Conn{request_path: request_path} = conn, content_type) do
     Logger.info(request_path)