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mmd - Miniature Markdown Library

Version Apache 2.0 Build Status Coverity Scan Status

mmd is a miniature markdown parsing "library" consisting of a single C source file and accompanying header file. mmd mostly conforms to the CommonMark version of markdown syntax with the following exceptions:

  • Embedded HTML markup and entities are explicitly not supported or allowed; the reason for this is to better support different kinds of output from the markdown "source", including XHTML, man, and xml2rfc.

  • Tabs are silently expanded to the markdown standard of four spaces since HTML uses eight spaces per tab.

  • Some pathological nested link and inline style features supported by CommonMark (******Really Strong Text******) are not supported by mmd.

In addition, mmd supports a couple (otherwise undocumented) markdown extensions:

  • Metadata as used by Jekyll and other web markdown solutions.

  • "@" links which resolve to headings within the file.

  • Tables and task lists as used by the Github Flavored Markdown Spec.

mmd also includes a standalone utility called mmdutil that can be used to generate HTML and man page source from markdown.

I'm providing mmd as open source under the Apache License Version 2.0 with exceptions for use with GPL2/LGPL2 applications which allows you do pretty much do whatever you like with it. Please do provide feedback and report bugs to the Github project page at so that everyone can benefit.


You'll need a C compiler.

How to Incorporate in Your Project

Add the mmd.c and mmd.h files to your project. Include the mmd.h header in any file that needs to read/convert markdown files.

"Kicking the Tires"

The supplied makefile allows you to build the unit tests on Linux and macOS (at least), which verify that all of the functions work as expected to produce a HTML file called testmmd.html:

make test

The makefile also builds the mmdutil program.

Installing mmdutil

You can install the mmdutil program by copying it to somewhere appropriate or run:

make install

to install it in /usr/local along with a man page.

Changes in v2.0

  • Added mxmlLoadString API and added a document pointer to the other load functions to allow concatenation of markdown files.
  • Fixed an issue with headings directly after a table.

Changes in v1.9

  • Added support for the Github-flavored markdown task list extension (check boxes in lists)
  • Addressed some issues found by the Clang static analyzer.

Changes in v1.8

  • Markdown of the form ([title](link)) did not parse correctly.
  • Addressed an issue identified by the LGTM code scanner.
  • Addressed some issues identified by the Cppcheck code scanner.
  • Addressed some issues identified by the Coverity code scanner.
  • Changed the makefile to only run the unit test program when using the "test" target.
  • Added a Cppcheck target ("cppcheck") to use this code scanning program against the mmd sources.

Changes in v1.7

The following changes were made for v1.7:

  • Fixed table parsing (Issue #11)
  • Fixed block-quoted Setext heading parsing.

Changes in v1.6

The following changes were made for v1.6:

  • Fixed some parsing bugs (Issue #7)
  • Fixed a crash bug in mmdutil (Issue #8)
  • Code fences using "~~~" are now supported.
  • Auto-links now properly handle preceding text (Issue #8)
  • Inline styles can now span multiple lines (Issue #8)
  • Links can now span multiple lines (Issue #8)
  • Shortcut links ([reference]) didn't work (Issue #8)
  • Fixed some issues with inline styles being incorrectly applied for things like "* *".
  • The testmmd program now supports running tests from the CommonMark specification and/or from the CommonMark test suite (Issue #9)
  • More CommonMark features (code languages, link titles, space-filled thematic breaks) and edge cases are now supported (Issue #10)
  • Added new mmdGetOptions and mmdSetOptions functions to control which extensions are supported.
  • Added new mmdGetExtra function to get the link title or code language string associated with certain nodes.

Changes in v1.5

The following changes were made for v1.5:

  • Added support for referenced links (Issue #1)
  • Added support for __bold__, _italic_, ~~strikethrough~~, and hard line breaks (Issue #4)

Changes in v1.4

The following changes were made for v1.4:

  • Fixed a table parsing bug where trailing pipes would add empty cells on the right side.
  • Tweaked the mmdutil program's default HTML stylesheet.
  • Fixed mmdutil error messages that incorrectly called the program mmdbook.
  • Fixed some Clang static analyzer warnings in mmd.c.
  • Fixed a build issue with Visual Studio.

Changes in v1.3

The following changes were made for v1.3:

  • Added mmdCopyAllText function that returns all of the text under the given node.
  • Added mmdutil program for converting markdown to HTML and man files.

Changes in v1.2

The following changes were made for v1.2:

  • Changed license to Apache License Version 2.0
  • Added support for markdown tables (Issue #3)

Changes in v1.1

The following changes were made for v1.1:

  • The mmd.h header now includes the C++ extern "C" wrapper around the C function prototypes.
  • Added a mmdLoadFile function that loads a markdown document from a FILE pointer.
  • Fixed a parsing bug for emphasized, bold, and code text containing whitespace.
  • Fixed a parsing bug for escaped characters followed by unescaped formatting sequences.
  • Fixed a parsing bug for headings that follow a list.

Legal Stuff

Copyright © 2017-2022 by Michael R Sweet.

mmd is licensed under the Apache License Version 2.0 with an (optional) exception to allow linking against GPL2/LGPL2-only software. See the files "LICENSE" and "NOTICE" for more information.