Recently maintained projects

JavaScript

• commonmark.js (reference implementation) - npm install commonmark
• markdown-it (high speed pluggable implementation) - npm install markdown-it
• html2commonmark (find your way back from html to markdown using the commonmark spec) npm install html2commonmark

C

• cmark (reference implementation, high performance executable and library)

C#

• CommonMark.NET - available on NuGet

Go

• opennota - pure Go implementation
• go-commonmark (wraps the C library)

Haskell

• cmark (wraps the C library)

Java

• commonmark-java - pure Java

Perl

• CommonMark (wraps the C library)

PHP

• league/commonmark - Based on the JS/C++ reference implementations

Python

• CommonMark-py - Pure Python implementation based on commonmark.js

Lua

• cmark-lua (wraps the C library) - luarocks install cmark
• lcmark (higher level interface around cmark, adding YAML metadata, filters, and templates)

Elixir

• Cmark

Dart

• md_proc

Ruby/RubyMotion

• CommonMarker (wraps the C library)
• motion-markdown-it - Based on the JS markdown-it library, ported to Ruby and RubyMotion

R

• commonmark (wraps the C library)

Rust

• pulldown-cmark

Swift

• SwiftMark

TypeScript

• DefinitelyTyped (JS library bindings, NuGet)

Not recently maintained

These projects are based on earlier versions of CommonMark and are now obsolete. But they might be good starting points for new work.

Python

• pycommonmark

Idris

• idris-commonmark

Haxe

• comark

Swift

• CommonMark.swift

Lua

• luacmark
• commonmark-lua - luajit + FFI