rolandshoemaker/stmd

Markdown is a popular way to write formatted text using simple symbols instead of a complex editor. The catch is that the original Markdown rules were ambiguous, so different tools interpret the same text differently, your document might look great in one app and broken in another. CommonMark (originally called stmd) fixes this by providing a precise, standardized specification for Markdown syntax, along with working tools that convert Markdown into HTML consistently. The project includes two implementations of this spec: one in C and one in JavaScript. The C version is a lightweight program and library with no external dependencies, so it can be dropped into almost any environment. You pass it a Markdown file and it outputs clean HTML. The JavaScript version is a single file you can embed in a web page, plus a command-line version for Node.js. There's also an interactive "dingus" you can launch locally to type Markdown and see the output in real time. This would be useful for anyone building a blogging platform, a documentation site, a note-taking app, or any product where users write in Markdown and expect it to render predictably. Instead of guessing how nested lists or code blocks should behave, you get a well-tested reference implementation with over 400 built-in conformance examples that double as a test suite. The specification itself is written from a writer's perspective rather than a machine's, it describes what counts as a block quote or a heading in plain English, rather than documenting a specific algorithm. The author drew on years of experience building Markdown parsers and deliberately kept the scope to core formatting, avoiding extensions like footnotes until the basics are nailed down. A few small additions, like fenced code blocks, were included because they had become near-universal conventions across existing tools.