diff --git a/lib/Atom.ex b/lib/Atom.ex
new file mode 100644
index 0000000..51ab779
--- /dev/null
+++ b/lib/Atom.ex
@@ -0,0 +1,92 @@
+defmodule FastRSS.Atom do
+  @type feed :: %{
+          title: text(),
+          id: String.t(),
+          updated: String.t(),
+          authors: list(person()),
+          categories: list(category()),
+          contributors: list(person()),
+          generator: generator() | nil,
+          icon: String.t() | nil,
+          links: list(link()),
+          logo: String.t() | nil,
+          rights: text() | nil,
+          subtitle: text() | nil,
+          entries: list(entry()),
+          extensions: map(),
+          namespaces: map(),
+          base: String.t() | nil,
+          lang: String.t() | nil
+        }
+
+  @type person :: %{
+          name: String.t(),
+          email: String.t() | nil,
+          uri: String.t() | nil
+        }
+
+  @type category :: %{
+          term: String.t(),
+          scheme: String.t() | nil,
+          label: String.t() | nil
+        }
+
+  @type generator :: %{
+          value: String.t(),
+          uri: String.t() | nil,
+          version: String.t() | nil
+        }
+
+  @type link :: %{
+          href: String.t(),
+          rel: String.t(),
+          hreflang: String.t() | nil,
+          mime_type: String.t() | nil,
+          title: String.t() | nil,
+          length: String.t() | nil
+        }
+
+  @type entry :: %{
+          title: text(),
+          id: String.t(),
+          updated: DateTime.t(),
+          authors: list(person()),
+          categories: list(category()),
+          contributors: list(person()),
+          links: list(link()),
+          published: String.t() | nil,
+          rights: text() | nil,
+          source: source() | nil,
+          summary: text() | nil,
+          content: content() | nil,
+          extensions: map()
+        }
+
+  @type content :: %{
+          base: String.t() | nil,
+          lang: String.t() | nil,
+          value: String.t() | nil,
+          src: String.t() | nil,
+          content_type: String.t() | nil
+        }
+
+  @type source :: %{
+          title: text(),
+          id: String.t(),
+          updated: DateTime.t(),
+          authors: list(person()),
+          categories: list(category()),
+          contributors: list(person()),
+          generator: generator() | nil,
+          icon: String.t() | nil,
+          links: list(link()),
+          logo: String.t() | nil,
+          rights: text() | nil,
+          subtitle: text() | nil
+        }
+
+  @type text :: %{
+          content: String.t(),
+          type: String.t() | nil
+        }
+end
diff --git a/lib/RSS.ex b/lib/RSS.ex
new file mode 100644
index 0000000..6a0d80d
--- /dev/null
+++ b/lib/RSS.ex
@@ -0,0 +1,148 @@
+defmodule FastRSS.RSS do
+  @type channel :: %{
+          title: String.t(),
+          link: String.t(),
+          description: String.t(),
+          language: String.t() | nil,
+          copyright: String.t() | nil,
+          managing_editor: String.t() | nil,
+          webmaster: String.t() | nil,
+          pub_date: String.t() | nil,
+          last_build_date: String.t() | nil,
+          categories: list(category()),
+          generator: String.t() | nil,
+          docs: String.t() | nil,
+          cloud: cloud() | nil,
+          rating: String.t() | nil,
+          ttl: String.t() | nil,
+          image: image() | nil,
+          text_input: text_input() | nil,
+          skip_hours: list(String.t()),
+          skip_days: list(String.t()),
+          items: list(item()),
+          extensions: map(),
+          itunes_ext: itunes_channel_extension() | nil,
+          dublin_core_ext: dublin_core_extension() | nil,
+          syndication_ext: syndication_extension() | nil,
+          namespaces: map()
+        }
+
+  @type cloud :: %{
+          domain: String.t(),
+          port: String.t(),
+          path: String.t(),
+          register_procedure: String.t(),
+          protocol: String.t()
+        }
+
+  @type image :: %{
+          url: String.t(),
+          title: String.t(),
+          link: String.t(),
+          width: String.t() | nil,
+          height: String.t() | nil,
+          description: String.t() | nil
+        }
+
+  @type text_input :: %{
+          title: String.t(),
+          description: String.t(),
+          name: String.t(),
+          link: String.t()
+        }
+
+  @type item :: %{
+          title: String.t() | nil,
+          link: String.t() | nil,
+          description: String.t() | nil,
+          author: String.t() | nil,
+          categories: list(category()),
+          comments: String.t() | nil,
+          enclosure: enclosure() | nil,
+          guid: guid() | nil,
+          pub_date: String.t() | nil,
+          source: source() | nil,
+          content: String.t() | nil,
+          extensions: map(),
+          itunes_ext: itunes_item_extension() | nil,
+          dublin_core_ext: dublin_core_extension() | nil
+        }
+
+  @type category :: %{
+          name: String.t(),
+          domain: String.t() | nil
+        }
+
+  @type enclosure :: %{
+          url: String.t(),
+          length: String.t(),
+          mime_type: String.t()
+        }
+
+  @type guid :: %{
+          value: String.t(),
+          permalink: boolean()
+        }
+
+  @type itunes_channel_extension :: %{
+          author: String.t() | nil,
+          block: String.t() | nil,
+          categories: list(itunes_category()),
+          image: String.t() | nil,
+          explicit: String.t() | nil,
+          complete: String.t() | nil,
+          new_feed_url: String.t() | nil,
+          owner: itunes_owner() | nil,
+          subtitle: String.t() | nil,
+          summary: String.t() | nil,
+          keywords: String.t() | nil,
+          type: String.t() | nil
+        }
+
+  @type dublin_core_extension :: %{
+          contributors: list(String.t()),
+          coverages: list(String.t()),
+          creators: list(String.t()),
+          dates: list(String.t()),
+          descriptions: list(String.t()),
+          formats: list(String.t()),
+          identifiers: list(String.t()),
+          languages: list(String.t()),
+          publishers: list(String.t()),
+          relations: list(String.t()),
+          rights: list(String.t()),
+          sources: list(String.t()),
+          subjects: list(String.t()),
+          titles: list(String.t()),
+          types: list(String.t())
+        }
+
+  @type syndication_extension :: %{
+          period: atom(),
+          frequency: non_neg_integer(),
+          base: String.t()
+        }
+
+  @type source :: %{
+          url: String.t(),
+          title: String.t()
+        }
+
+  @type itunes_category :: String.t()
+
+  @type itunes_owner :: %{
+          name: String.t() | nil,
+          email: String.t() | nil
+        }
+
+  @type itunes_item_extension :: %{
+          author: String.t() | nil,
+          block: String.t() | nil,
+          duration: String.t() | nil,
+          explicit: String.t() | nil,
+          keywords: String.t() | nil,
+          subtitle: String.t() | nil,
+          summary: String.t() | nil,
+          title: String.t() | nil
+        }
+end
diff --git a/lib/fast_rss.ex b/lib/fast_rss.ex
index eef559c..10ac5cf 100644
--- a/lib/fast_rss.ex
+++ b/lib/fast_rss.ex
@@ -29,7 +29,7 @@ defmodule FastRSS do
   @doc since: "0.5.0"
   @deprecated "Use FastRSS.parse_rss/1 instead"
   """
-  @spec parse(String.t()) :: {:ok, map()} | {:error, String.t()}
+  @spec parse(String.t()) :: {:ok, FastRSS.RSS.channel()} | {:error, String.t()}
   def parse(""), do: {:error, "Cannot parse blank string"}
   def parse(rss_string) when is_binary(rss_string), do: parse_rss(rss_string)
   def parse(_something_else), do: {:error, "RSS feed must be passed in as a string"}
@@ -37,7 +37,7 @@ defmodule FastRSS do
   @doc """
   Parse a RSS string into a map.
   """
-  @spec parse_rss(String.t()) :: {:ok, map()} | {:error, String.t()}
+  @spec parse_rss(String.t()) :: {:ok, FastRSS.RSS.channel()} | {:error, String.t()}
   @doc since: "0.5.0"
   def parse_rss(""), do: {:error, "Cannot parse blank string"}
 
@@ -52,7 +52,7 @@ defmodule FastRSS do
   @doc """
   Parse a Atom string into a map.
   """
-  @spec parse_atom(String.t()) :: {:ok, map()} | {:error, String.t()}
+  @spec parse_atom(String.t()) :: {:ok, FastRSS.Atom.feed()} | {:error, String.t()}
   @doc since: "0.5.0"
   def parse_atom(""), do: {:error, "Cannot parse blank string"}