MultiMarkdown, or MMD, is a tool to help turn minimally marked-up plain text into well formatted documents, including HTML, PDF (by way of LaTeX), OPML, or OpenDocument (specifically, Flat OpenDocument or ‘.fodt’, which can in turn be converted into RTF, Microsoft Word, or virtually any other word-processing format).

MMD is a superset of the Markdown syntax, originally created by John Gruber. It adds multiple syntax features (tables, footnotes, and citations, to name a few), in addition to the various output formats listed above (Markdown only creates HTML). Additionally, it builds in “smart” typography for various languages (proper left- and right-sided quotes, for example).