About Markdown Online

Markdown Online is a free, open-source Markdown tool — write, preview, import, and export, all in one page, all running in your browser. Paste or type Markdown (or HTML, CSV, JSON) in, get the result back, and nothing you typed ever crosses the network.

That constraint is deliberate. A lot of what people convert day to day — draft docs, internal notes, AI-assistant output — isn't something they want sitting on a third-party server, even briefly. Doing the conversion entirely in the browser with open libraries like marked, Turndown, and DOMPurify means there's no upload step to worry about in the first place.

Why this exists

Markdown is the glue language of AI — prompts, LLM output, and docs handed between tools all pass through it. AI enables extreme automation, entire workflows and apps built on top of it, yet a constant in day-to-day work is still copy-pasting Markdown from place to place. The tools to handle that well already exist, but they're scattered across ad-bloated online converters or locked inside heavy desktop apps like Obsidian or VS Code. This site puts writing, previewing, importing, and exporting Markdown in one lightweight page instead.

It was built primarily for the author's own use, then released as a free, open-source Markdown editor because the same daily itch isn't unique to one person. It's still actively developed — no ads, no tracking, no account, no email capture, just a tool. It's licensed under GPL-3.0 — see the GitHub repo for the full source and license text — because a tool this small has no business asking anything of the people who use it. Read the code, fork it, self-host it, send a pull request, or just leave a star — that's the best way to help push it forward.