A free web tool that turns Markdown (.md) into HTML and converts HTML back into Markdown. Nothing to install, no sign-up, and no file ever leaves your machine — every conversion runs inside your browser.
Markdown is pleasant to write but it does not look like a finished document on its own.
GitHub and Notion render it for you; the moment a .md file leaves those walls,
the reader sees raw #, ** and | characters.
That is where converting to HTML helps.
It does more than move paragraphs across. GFM tables and task lists, syntax highlighting for fenced code, Mermaid diagrams and LaTeX math (KaTeX) all come through. Mermaid diagrams are rendered to images before export, so whoever opens the file sees the diagram without installing anything.
Images work the same way. Drop in the picture files your document references and they are matched by filename and embedded directly into the HTML. What you get back is a single file with the images inside — attach it to an email or copy it to a USB stick and nothing breaks.
Converting HTML back to Markdown happens on the same screen. Drop an .html file,
paste content copied straight from a web page, or enter a URL and the page is fetched for you.
Tables and code-block languages are kept when converting back as well, which makes it a
practical way to pull something you read on the web into your own Markdown notes.
Conversion happens entirely in the browser and document contents are never transmitted. Internal documents and unpublished drafts are safe to use here. You can also drop several files at once, review them one by one, then download them individually or all together as a ZIP. The interface is available in English and Korean.
Running entirely in the browser sets a few limits, and it is easier if you know them up front. File size depends on your device's memory. A single huge Markdown file is rare, but adding dozens of images inflates the result: base64 encoding makes the exported file roughly 33% larger than the images themselves. If that pushes you past an email attachment limit, export without the images and send them separately.
Converting HTML back to Markdown drops anything Markdown has no syntax for — text colour, centred blocks, merged table cells. That is a limit of the format rather than of this tool, so no converter avoids it. If that formatting matters, keep the HTML as your source of truth.
Only the fetch-by-URL feature passes through a server, because browsers block reading documents from another domain directly. Even then the fetched page is used for the conversion and not stored. Pages behind a login, or sites that refuse automated requests, cannot be fetched.
You get one HTML file with the styles written inside it. It does not load external CSS, so it opens without a network connection and keeps its appearance when you attach it to an email or copy it to a USB stick. Syntax highlighting travels with it too — the colours are baked into the file.
Mermaid diagrams are rendered to images before export, so whoever opens the file sees the diagram without knowing what Mermaid is. Math is typeset with KaTeX and the font information it needs is included. If a document has neither diagrams nor math, those engines are never downloaded and the page stays light.