Renders Markdown to HTML as you type, so you can check a README, an issue comment or a post before publishing it. The gap between what you wrote and what renders is usually a list that needed a blank line above it, or a code fence that was never closed.
Flavours differ. Tables, task lists, strikethrough and autolinking are GitHub Flavoured Markdown extensions rather than part of the original spec, so a document that renders correctly here can look different in a tool that implements only the base syntax.
Frequently asked questions
Is the rendered HTML safe?
Yes — and this genuinely matters, because Markdown allows raw HTML, so an input containing <img src=x onerror=…> would otherwise be a live XSS vector. The rendered output is passed through DOMPurify before display, which strips scripts, event handlers and dangerous attributes. Sanitising the parsed DOM rather than escaping the input text is what makes it resistant to mutation-XSS tricks.
Why does a single newline not create a line break?
Because CommonMark treats consecutive lines as one paragraph — that is the specification. GitHub comments deviate from this and break on every newline, which is why the "breaks" option exists. Turn it on to match GitHub, leave it off to match the spec and most static site generators.
Which Markdown flavour is supported?
CommonMark plus GitHub Flavored Markdown extensions: tables, task lists, strikethrough and autolinks. Platform-specific syntax such as Obsidian wiki-links or MDX components is not rendered.