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ExDoc is a tool to generate documentation for your Elixir projects. In case you are looking for documentation for Elixir itself, check out Elixir's website.

To learn about how to document your projects check out Elixir's writing documentation page.

See the ExDoc Documentation.

Using ExDoc with Mix

To use ExDoc in your Mix projects, first add ExDoc as a dependency.

If you are using Elixir v1.7 and later:

def deps do
    {:ex_doc, "~> 0.19", only: :dev, runtime: false},

If you are using Elixir v1.6 and earlier:

def deps do
    {:ex_doc, "~> 0.18.0", only: :dev, runtime: false},

After adding ExDoc as a dependency, run mix deps.get to install it.

ExDoc will automatically pull in information from your projects, like the application and version. However, you may want to set :name, :source_url and :homepage_url to have a nicer output from ExDoc, such as:

def project do
    app: :my_app,
    version: "0.1.0-dev",
    deps: deps(),

    # Docs
    name: "MyApp",
    source_url: "https://github.com/USER/PROJECT",
    homepage_url: "http://YOUR_PROJECT_HOMEPAGE",
    docs: [
      main: "MyApp", # The main page in the docs
      logo: "path/to/logo.png",
      extras: ["README.md"]

Now you are ready to generate your project documentation with mix docs. To see all options available when generating docs, run mix help docs.

Using ExDoc via command line

You can ExDoc via the command line as follows:

  1. Install ExDoc as an escript:

    $ mix escript.install hex ex_doc
  2. Then you are ready to use it in your projects. First, move into your project directory and make sure it is already compiled:

    $ mix compile
  3. Next invoke the ex_doc executable from your project:

    $ ex_doc "PROJECT_NAME" "PROJECT_VERSION" path/to/project/ebin -m "PROJECT_MODULE" -u "https://github.com/GITHUB_USER/GITHUB_REPO" -l path/to/logo.png
  4. By default, ex_doc produces HTML files, but, you can also create a EPUB document passing the option --formatter epub:

    $ PATH_TO_YOUR_EXDOC/bin/ex_doc "PROJECT_NAME" "PROJECT_VERSION" path/to/project/ebin -m "PROJECT_MODULE" -u "https://github.com/GITHUB_USER/GITHUB_REPO" -l path/to/logo.png -f epub

For example, here are some acceptable values:

PROJECT_MODULE  => Ecto (the main module provided by the library)
GITHUB_USER     => elixir-lang
GITHUB_REPO     => ecto


ExDoc will automatically generate links across modules and functions if you enclose them in backticks:

  • By referring to a module, function, type or callback from your project, such as `MyModule`, ExDoc will automatically link to those
  • By referring to a module, function, type or callback from Elixir, such as [`String`](https://hexdocs.pm/elixir/String.html), ExDoc will automatically link to Elixir's stable documentation
  • By referring to a module or function from erlang, such as (`:erlang`), ExDoc will automatically link to the Erlang documentation
  • By referring to a module, function, type or callback from any of your dependencies, such as `MyDep`, ExDoc will automatically link to that dependency documentation on hexdocs.pm (the link can be configured by setting docs: [deps: [my_dep: "https://path/to/docs/"]] in your mix.exs)

ExDoc supports linking to modules (`MyModule`), functions (`MyModule.function/1`), types (`t:MyModule.type/2`) and callbacks (`c:MyModule.callback/3`). If you want to link a function, type or callback in the current module, you may skip the module name, such as `function/1`.

Changing the Markdown tool

In the examples above, we have used Earmark to convert Markdown to HTML. If you prefer, you can also use cmark (in C).


Cmark is a CommonMark parser written in C. To use cmark add the elixir NIF wrapper cmark.ex as a dependency to your project:

{:cmark, "~> 0.6", only: :dev}

Update your project configuration to use Cmark:

docs: [markdown_processor: ExDoc.Markdown.Cmark]


The easiest way to test changes to ExDoc is to locally re-generate it's own docs:

  1. Run mix setup to install all dependencies
  2. Run mix build to generate docs. This is a custom alias that will build assets, recompile ExDoc, and output fresh docs into the doc/ directory
  3. Commit both assets/* and formatters/* changes (after running mix build)


ExDoc source code is released under Apache 2 License. The generated contents, however, are under different licenses based on projects used to help render HTML, including CSS, JS, and other assets.

Check the LICENSE file for more information.