leandrocp

MDEx - Fast and Extensible Markdown

MDEx is a fast and extensible Markdown parser and formatter.

Fast

Leverage Rust to parse, manipulate and render documents using:

comrak - a Rust port of the official GitHub markdown library compliant with the CommonMark spec.
ammonia - HTML sanitization.
autumnus - syntax highlighter powered by Tree-sitter and Neovim themes.

Extensible

A Req-like API to manipulate documents in a pipeline with support for plugins, for eg mdex_mermaid

Features

Fast
Compliant with the CommonMark spec
Plugins
Formats:
- Markdown (CommonMark)
- HTML
- JSON
- XML
- Quill Delta
Floki-like Document AST
Req-like Document pipeline API
GitHub Flavored Markdown
Discord and GitLab Flavored-ish Markdown
Wiki-style links
Streaming incomplete fragments
Emoji shortcodes
Built-in Syntax Highlighting for code blocks
Code Block Decorators
HTML sanitization
~MD Sigil for Markdown, HTML, JSON, XML, and Quill Delta

More at GitHub - leandrocp/mdex: Markdown for Elixir. Fast, Extensible, Phoenix-native. AI-ready. Built on top of comrak, ammonia, and lumis. · GitHub

24 comments

#library #markdown #rustler #commonmark

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2026-01-21 19:58:59 UTC

Most Liked

leandrocp

MDEx v0.9 is now available with some new cool features!

Delta format

Thanks to @Jskalc we can now convert Markdown to Delta:

Streaming

Initial (experimental) support to put incomplete fragments of Markdown into the document. Useful for AI/LLM tools:

You can see a demo (video) at Leandro Pereira on X: "Here's a short demo of Markdown streaming in MDEx 👀 Note it's still experimental and disabled by default. https://t.co/uEdEEalbb8" / X

Inspect Document as a tree

To help visualize the nodes in a document:

It can be disabled if you prefer the regular struct inspect.

Unified Document API

Removed the MDEx.Pipe module in favor of unifying all operations in the MDEx.Document. Note this is a breaking change:

I’ll be working on Support Phoenix tags? · Issue #571 · kivikakk/comrak · GitHub so we can (hopefully) get Elixir and Phoenix components rendering inside Markdown. Enjoy!

Post #16

leandrocp

MDEx v0.7.0 is out with a new ~MD sigils supporting assigns and Elixir expressions:

import MDEx.Sigil

assigns = %{lang: "elixir", sample: "spawn(fn -> send(current, {self(), 1 + 2}) end)"}

~MD"""
## Lang: <%= String.capitalize(@lang) %>

```elixir
<%= @sample %>
```
"""

Outputs:

%MDEx.Document{
  nodes: [
    %MDEx.Heading{nodes: [%MDEx.Text{literal: "Lang: Elixir"}], level: 2, setext: false},
    %MDEx.CodeBlock{
      nodes: [],
      fenced: true,
      fence_char: "`",
      fence_length: 3,
      fence_offset: 0,
      info: "elixir",
      literal: "spawn(fn -> send(current, {self(), 1 + 2}) end)\n"
    }
  ]
}

Or using the HTML modifier:

"<h2>Lang: Elixir</h2>\n<pre class=\"athl\" style=\"color: #abb2bf; background-color: #282c34;\"><code class=\"language-elixir\" translate=\"no\" tabindex=\"0\"><span class=\"line\" data-line=\"1\"><span style=\"color: #61afef;\">spawn</span><span style=\"color: #848b98;\">(</span><span style=\"color: #c678dd;\">fn</span> <span style=\"color: #abb2bf;\">-&gt;</span> <span style=\"color: #61afef;\">send</span><span style=\"color: #848b98;\">(</span><span style=\"color: #abb2bf;\">current</span><span style=\"color: #848b98;\">,</span> <span style=\"color: #848b98;\">&lbrace;</span><span style=\"color: #61afef;\">self</span><span style=\"color: #848b98;\">(</span><span style=\"color: #848b98;\">)</span><span style=\"color: #848b98;\">,</span> <span style=\"color: #d19a66;\">1</span> <span style=\"color: #abb2bf;\">+</span> <span style=\"color: #d19a66;\">2</span><span style=\"color: #848b98;\">&rbrace;</span><span style=\"color: #848b98;\">)</span> <span style=\"color: #c678dd;\">end</span><span style=\"color: #848b98;\">)</span>\n</span></code></pre>"

That’s one step into the direction of supporting Markdown in LiveViews with components.

Post #10

leandrocp

MDEx v0.11 is out with 2 new cool features:

Initial support for Phoenix Components

Now you can render Phoenix Components inside Markdow, either inside a LiveView or just use the ~MD[...]HEEX sigil. Example:

def render(assigns) do
  ~MD"""
  Hello from MDEx :wave:

  Today is _{Calendar.strftime(DateTime.utc_now(), "%B %d, %Y")}_

  <ReqEmbed.embed url={@video_url} class="aspect-video rounded-xl my-6" />

  Built with:
  - <.link href="https://crates.io/crates/comrak">comrak</.link>
  - <.link href="https://hex.pm/packages/mdex">MDEx</.link>
  """HEEX
end

More info at Phoenix LiveView HEEx — MDEx v0.13.2

Syntax Highlighter with Light/Dark themes

The syntax highlighting engine now supports dual/multi themes so you can have automatic light/dark themes:

options = [
  syntax_highlight: [
    formatter: {
      :html_multi_themes,
      themes: [light: "github_light", dark: "github_dark"],
      default_theme: "light-dark()"
    }
  ]
]

Full example at Lumis light/dark theme — MDEx v0.13.2

I’m also opening a sponsorship program if you want to support MDEx in that way please see GitHub - leandrocp/mdex: Markdown for Elixir. Fast, Extensible, Phoenix-native. AI-ready. Built on top of comrak, ammonia, and lumis. · GitHub

Post #19