MDEx

Fast and Extensible Markdown for Elixir.

Features

• Fast
• Compliant with the CommonMark spec
• Plugins
• Formats:
  • Markdown (CommonMark)
  • HTML
  • Phoenix HEEx
  • 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
• Phoenix HEEx components and expressions
• Streaming incomplete fragments
• Emoji shortcodes
• Built-in Syntax Highlighting for code blocks
• Code Block Decorators
• HTML sanitization
• ~MD Sigil for Markdown, HTML, HEEx, JSON, XML, and Quill Delta

Installation

Add :mdex dependency:

def deps do
  [
    {:mdex, "~> 0.10"}
  ]
end

Or use Igniter:

mix igniter.install mdex

Usage

iex> MDEx.to_html!("# Hello :smile:", extension: [shortcodes: true])
"<h1>Hello 😄</h1>"

iex> MDEx.new(markdown: "# Hello :smile:", extension: [shortcodes: true]) |> MDEx.to_html!()
"<h1>Hello 😄</h1>"

iex> import MDEx.Sigil
iex> ~MD[# Hello :smile:]HTML
"<h1>Hello 😄</h1>"

iex> import MDEx.Sigil
iex> assigns = %{project: "MDEx"}
iex> ~MD[# {@project}]HEEX
%Phoenix.LiveView.Rendered{...}

iex> import MDEx.Sigil
iex> ~MD[# Hello :smile:]
#MDEx.Document(3 nodes)<
├── 1 [heading] level: 1, setext: false
│   ├── 2 [text] literal: "Hello "
│   └── 3 [short_code] code: "smile", emoji: "😄"
>

iex> MDEx.new(streaming: true)
...> |> MDEx.Document.put_markdown("**Install")
...> |> MDEx.to_html!()
"<p><strong>Install</strong></p>"

Examples

Livebook examples are available at Pages / Examples

Foundation

The library is built on top of:

• comrak - a fast Rust port of GitHub's CommonMark parser
• ammonia for HTML Sanitization
• autumnus for Syntax Highlighting

Used By

• BeaconCMS
• Tableau
• Bonfire
• 00
• Plural Console
• Exmeralda
• Algora
• Ash AI
• Canada Navigator
• And more...

Are you using MDEx and want to list your project here? Please send a PR!

Sponsors

💜 Support MDEx Development

If you or your company find MDEx useful, please consider sponsoring its development.

➡️ GitHub Sponsors

Your support helps maintain and improve MDEx for the entire Elixir community!

Current and previous sponsors

Motivation

MDEx was born out of the necessity of parsing CommonMark files, to parse hundreds of files quickly, and to be easily extensible by consumers of the library.

• earmark is extensible but can't parse all kinds of documents and is slow to convert hundreds of markdowns.
• md is very extensible but the doc says "If one needs to perfectly parse the common markdown, Md is probably not the correct choice" and CommonMark was a requirement to parse many existing files.
• 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, is hard to extend, and was archived on Apr 2024.

Comparison

Feature	MDEx	Earmark	md	cmark
Active	✅	✅	✅	❌
Pure Elixir	❌	✅	✅	❌
Extensible	✅	✅	✅	❌
Syntax Highlighting	✅	❌	❌	❌
Code Block Decorators	✅	❌	❌	❌
Streaming (fragments)	✅	❌	❌	❌
Phoenix HEEx components	✅	❌	❌	❌
AST	✅	✅	✅	❌
AST to Markdown	✅	⚠️²	❌	❌
To HTML	✅	✅	✅	✅
To JSON	✅	❌	❌	❌
To XML	✅	❌	❌	✅
To Manpage	❌	❌	❌	✅
To LaTeX	❌	❌	❌	✅
To Quill Delta	✅	❌	❌	❌
Emoji	✅	❌	❌	❌
GFM³	✅	✅	❌	❌
GitLab⁴	⚠️¹	❌	❌	❌
Discord⁵	⚠️¹	❌	❌	❌

1. Partial support
2. Possible with earmark_reversal
3. GitHub Flavored Markdown
4. GitLab Flavored Markdown
5. Discord Flavored Markdown

Benchmark

A benchmark is available to compare existing libs:

Name              ips        average  deviation         median         99th %
mdex          8983.16       0.111 ms     ±6.52%       0.110 ms       0.144 ms
md             461.00        2.17 ms     ±2.64%        2.16 ms        2.35 ms
earmark        110.47        9.05 ms     ±3.17%        9.02 ms       10.01 ms

Comparison:
mdex          8983.16
md             461.00 - 19.49x slower +2.06 ms
earmark        110.47 - 81.32x slower +8.94 ms

Memory usage statistics:

Name            average  deviation         median         99th %
mdex         0.00184 MB     ±0.00%     0.00184 MB     0.00184 MB
md              6.45 MB     ±0.00%        6.45 MB        6.45 MB
earmark         5.09 MB     ±0.00%        5.09 MB        5.09 MB

Comparison:
mdex         0.00184 MB
md              6.45 MB - 3506.37x memory usage +6.45 MB
earmark         5.09 MB - 2770.15x memory usage +5.09 MB

The most performance gain is using the ~MD sigil to compile the Markdown instead of parsing it at runtime, prefer using it when possible.

To finish, a friendly reminder that all libs have their own strengths and trade-offs so use the one that better suits your needs.

Acknowledgements

• comrak crate for all the heavy work on parsing Markdown and rendering HTML
• Floki for the AST
• Req for the pipeline API
• Logo based on markdown-mark