CommonMark

CommonMark is an unambiguous specification and test suite for the Markdown markup language, created to resolve inconsistencies that had let different implementations of Markdown diverge from one another. The effort began in 2012 under the name Standard Markdown, led by a group of developers including Jeff Atwood and John MacFarlane, and was renamed CommonMark in September 2014 after Markdown's original author John Gruber objected to the word Markdown appearing in the project's name. The first released version of the specification appeared on October 25, 2014, with the specification continuing to be revised since, reaching version 0.31.2 in January 2024. CommonMark exists because Markdown's original informal description contained ambiguities and left unanswered questions, causing separate implementations to diverge both intentionally and accidentally; CommonMark is now used as the reference specification by major platforms including GitHub, GitLab, Reddit and Stack Overflow.