Markdown to HTML

BrainCoder's Markdown to HTML converter turns Markdown into an HTML fragment you can paste straight into a page, an email, a CMS field or a component. It parses CommonMark plus the GitHub extensions — headings, ordered and unordered lists, tables, fenced code with a language class, task lists, strikethrough, blockquotes, links and images with alt text — and the HTML pane updates as you type. A Preview tab renders exactly the same HTML, so the string you copy is the string you looked at.

The output is sanitized before it is shown, copied or downloaded. Raw inline HTML inside your Markdown is rendered as HTML, then the whole document is filtered against an allowlist: <script>, event handlers such as onclick, unsafe URLs like javascript:, iframes, <style>, embedded SVG and form controls are removed, tags outside the allowlist are unwrapped (their text survives, the tag does not), an <a> that loses an unsafe URL keeps its text but loses the href, and HTML comments are dropped.

There is an optional highlight step for reading code quickly: the checkbox wraps fenced code in <span class="tok tok-keyword"> markup. It comes from a small built-in highlighter for JavaScript, TypeScript, JSON, HTML, CSS, Python, shell, SQL, YAML and Markdown — it is regex-based, not a full parser, so unusual syntax can be mis-marked. It is off by default, so the HTML you normally copy stays clean.

Everything runs in this tab. The Markdown, the generated HTML and any file you open are read locally and nothing is uploaded. The input is capped at 200,000 characters — the editor stops accepting input at the cap and a larger file is refused with the limit stated. Copy writes the exact sanitized fragment; Download writes a standalone HTML document (a doctype, a charset tag, one inline stylesheet and no scripts) named after the file you opened, or after the name you type, with markdown.html as the disclosed placeholder when you are pasting.