sundown是一个 C写的gfm 风格markdown的parser，当然ruby,python什么的都有对它的wrapper。

特性：

• 完全符合标准

  Sundown passes out of the box the official Markdown v1.0.0 and v1.0.3 test suites, and has been extensively tested with additional corner cases to make sure its output is as sane as possible at all times.

• 大规模的扩展支持

  Sundown has optional support for several (unofficial) Markdown extensions, such as non-strict emphasis, fenced code blocks, tables, autolinks, strikethrough and more.

• UTF-8 aware

  Sundown is fully UTF-8 aware, both when parsing the source document and when generating the resulting (X)HTML code.

• Tested & Ready to be used on production

  Sundown has been extensively security audited, and includes protection against all possible DOS attacks (stack overflows, out of memory situations, malformed Markdown syntax...) and against client attacks through malicious embedded HTML.

  We've worked very hard to make Sundown never crash or run out of memory under any input. Sundown renders all the Markdown content in GitHub and so far hasn't crashed a single time.

• Customizable renderers

  Sundown is not stuck with XHTML output: the Markdown parser of the library is decoupled from the renderer, so it's trivial to extend the library with custom renderers. A fully functional (X)HTML renderer is included.

• Optimized for speed

  Sundown is written in C, with a special emphasis on performance. When wrapped on a dynamic language such as Python or Ruby, it has shown to be up to 40 times faster than other native alternatives.

• Zero-dependency

  Sundown is a zero-dependency library composed of 3 .c files and their headers. No dependencies, no bullshit. Only standard C99 that builds everywhere.

项目主页：http://www.open-open.com/lib/view/home/1394767078290