I just released cmark 0.18.2. cmark is the C reference implementation of CommonMark. The main exciting new feature is a CommonMark renderer: cmark can now write CommonMark as well as read it.
I have updated my Haskell bindings, and I am already using this library in the development version of pandoc. Once pandoc 1.14 is released, you’ll be able to use pandoc to convert reliably from CommonMark to many other formats, including HTML, LaTeX, reStructuredText, MediaWiki markup, DocBook, various other flavors of Markdown, Word docx, and EPUB. (All of these formats can also be translated to CommonMark using pandoc.)