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- https://github.com/markdown-it/markdown-it - supports plugins, http://www.broculos.net/2015/12/build-your-own-markdown-flavour-with.html
- https://github.com/jgm/commonmark.js
- https://github.com/evilstreak/markdown-js, used by discourse https://meta.discourse.org/t/discourse-has-a-new-markdown-parser/9318, https://github.com/discourse/discourse/tree/master/app/assets/javascripts/discourse/dialects - their additions
- http://strapdownjs.com/
- https://github.com/jonschlinkert/remarkable
- https://github.com/brrd/celldown.js - helper for handling markdown tables
- https://casual-effects.com/markdeep/ - BSD, many interesting features
- https://github.com/showdownjs/showdown
- https://github.com/chjj/marked
- https://github.com/GitbookIO/kramed - fork of marked with decent amount of improvements
- https://github.com/bevacqua/ultramarked
- https://code.google.com/p/markdownsharp/ - C# implementation of markdown parser, used on Stack Overflow
- https://github.com/lunet-io/markdig : C# implementation
- http://mistune.readthedocs.org/en/latest/ : pure python
- http://commonmark.org/ : c and JavaScript
- https://github.com/Knagis/CommonMark.NET - port of stmd
- https://github.com/gomarkdown/markdown : Go
- https://github.com/russross/blackfriday/commits/v2 : Go
- http://marklighteditor.com/
- https://stackedit.io/app#, https://github.com/benweet/stackedit
- http://prose.io/
- http://marxi.co/ - syncs to evernote
- https://www.beyondpad.com/app#notes/inbox
- http://dillinger.io/
- https://www.gitbook.com/book/kjk/test-book/edit#/edit/master/README.md
- http://markup.rocks/
- http://jbt.github.io/markdown-editor/
- https://github.com/bevacqua/woofmark
- http://summernote.org/
- https://www.froala.com/wysiwyg-editor/v2.0
- https://github.com/basecamp/trix
- http://codegeekz.com/markdown-editors-and-tools/
- http://mouapp.com/
- http://clockworkengine.com/lightpaper-mac/
- http://markdownpad.com/
- http://mike-ward.net/markdownedit/ - WPF, metro-style, open-source
- http://realmacsoftware.com/typed
- https://github.com/leeoniya/reMarked.js, http://leeoniya.github.io/reMarked.js/
- https://github.com/brrd/Abricotine - electron, gpl
- https://markdowner.github.io/ : preview markdown ⇒ html
- http://johnmacfarlane.net/babelmark2 : compare various implementations
- https://github.com/domchristie/to-markdown - html to markdown in javascript
- https://github.com/leeoniya/reMarked.js - html to markdown in javascript
- https://spec.commonmark.org/dingus/ : shows ast of markdown parsed as commonmark
- https://babelmark.github.io/ : shows how different implementation parse the same markdown content
- https://github.com/mangini/gdocs2md : google docs to markdown