View Source MDEx (MDEx v0.1.16)

MDEx logo

A fast 100% CommonMark-compatible GitHub Flavored Markdown parser and formatter for Elixir.

Hex Version Hex Docs MIT


Check out some samples at


Add :mdex dependecy:

def deps do
    {:mdex, "~> 0.1"}


Mix.install([{:mdex, "~> 0.1"}])
MDEx.to_html("# Hello")
#=> "<h1>Hello</h1>\n"
# MDEx

Some benefits you'll find:
- Fast
- CommonMark spec
- Binary is precompiled, no need to compile anything
""") |> IO.puts()
#=> <h1>MDEx</h1>
#=> <p>Some benefits you'll find:</p>
#=> <ul>
#=> <li>Fast</li>
#=> <li>CommonMark spec</li>
#=> <li>Binary is precompiled, no need to compile anything</li>
#=> <li>Easier to work with since it's Rust</li>
#=> </ul>
# And more...

* Built-in code syntax highlight

""") |> IO.puts()
#=> <h1>And more...</h1>
#=> <ul>
#=> <li>Built-in code syntax highlight</li>
#=> </ul>
#=> <pre class="autumn-hl" style="background-color: #282C34; color: #ABB2BF;">
#=> <code class="language-elixir" translate="no">
#=> <span class="ahl-namespace" style="color: #61AFEF;">String</span><span class="ahl-operator" style="color: #C678DD;">.</span><span class="ahl-function" style="color: #61AFEF;">upcase</span><span class="ahl-punctuation ahl-bracket" style="color: #ABB2BF;">(</span><span class="ahl-string" style="color: #98C379;">&quot;elixir&quot;</span><span class="ahl-punctuation ahl-bracket" style="color: #ABB2BF;">)</span>
#=> </code></pre>

Demo and Samples

A livebook and a script are available to play with and experiment with this library,or you can check out all available samples at


A simple script is available to compare existing libs:

Name              ips        average  deviation         median         99th %
cmark         24.01 K      0.0417 ms    ±14.11%      0.0405 ms      0.0631 ms
mdex          16.37 K      0.0611 ms     ±9.65%      0.0601 ms      0.0870 ms
md             0.85 K        1.18 ms     ±4.72%        1.16 ms        1.36 ms
earmark        0.47 K        2.14 ms     ±2.82%        2.13 ms        2.42 ms

cmark         24.01 K
mdex          16.37 K - 1.47x slower +0.0194 ms
md             0.85 K - 28.36x slower +1.14 ms
earmark        0.47 K - 51.47x slower +2.10 ms


  • earmark can't parse all kinds of documents and is slow to convert hundreds of markdowns.
  • md is fast enough and extensible but the doc says "If one needs to perfectly parse the common markdown, Md is probably not the correct choice" so it also fails to parse many documents.
  • markdown is not precompiled and has not received updates in a while.
  • cmark is a fast CommonMark parser but it requires compiling the C library and is hard to extend.

But if any of the available libraries is working for you, you can keep using it :)

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Convert markdown to HTML.

Convert markdown to HTML with custom opts.


@spec to_html(String.t()) :: String.t()

Convert markdown to HTML.


iex> MDEx.to_html("# MDEx")

iex> MDEx.to_html("Implemented with:\n1. Elixir\n2. Rust")
"<p>Implemented with:</p>\n<ol>\n<li>Elixir</li>\n<li>Rust</li>\n</ol>\n"
@spec to_html(
) :: String.t()

Convert markdown to HTML with custom opts.


Accepts all available Comrak Options as keyword lists.

Features Options

  • :sanitize (default false) - sanitize output using ammonia. Recommended if passing render: [unsafe_: true]
  • :syntax_highlight_theme (default "onedark") - syntax highlight code fences using autumn themes, you should pass the filename without special chars and without extension, for example you should pass syntax_highlight_theme: "adwaita_dark" to use the Adwaita Dark theme.


iex> MDEx.to_html("# MDEx")

iex> MDEx.to_html("Implemented with:\n1. Elixir\n2. Rust")
"<p>Implemented with:</p>\n<ol>\n<li>Elixir</li>\n<li>Rust</li>\n</ol>\n"

iex> MDEx.to_html("Hello ~world~ there", extension: [strikethrough: true])
"<p>Hello <del>world</del> there</p>\n"

iex> MDEx.to_html("<marquee>visit https://</marquee>", extension: [autolink: true], render: [unsafe_: true])
"<p><marquee>visit <a href=\"https://\">https://</a></marquee></p>\n"

iex> MDEx.to_html("# Title with <script>console.log('dangerous script')</script>", render: [unsafe_: true], features: [sanitize: true])
"<h1>Title with </h1>\n"