How the Markdown converter works
Write or paste Markdown in the left editor, or load a .md, .markdown, or .txt file with Import File. Click Convert and the text is parsed by marked 12.0.2, an open-source Markdown parser that runs in your browser. The right editor shows the HTML source. It is not a rendered preview: you get the markup to copy into a CMS, template, or email, or to save as converted.html with Download Output.
Two parser settings shape the output:
- GitHub Flavored Markdown is on. Pipe tables, task lists (
- [x]), strikethrough (~~text~~), fenced code blocks, and bare URLs are all converted.
- Line breaks follow the standard. A single newline inside a paragraph is not a line break. End a line with two spaces, or start a new paragraph with a blank line.
The output is an HTML fragment: no <html>, <head>, or CSS. Paste it inside an existing page, or wrap it yourself.
Example: a release changelog
Markdown input:
## Changelog: v2.4.0
Released **2026-09-01**. See [the upgrade notes](https://example.com/upgrade).
- [x] Drop Node 16 support
- [ ] Migrate config to `app.config.js`
| Setting | Default | Notes |
|-----------|:-------:|------------------|
| `timeout` | 30 | Seconds |
| `retries` | 3 | ~~5~~ reduced |
```js
export default { timeout: 30 };
```
HTML output:
<h2>Changelog: v2.4.0</h2>
<p>Released <strong>2026-09-01</strong>. See <a href="https://example.com/upgrade">the upgrade notes</a>.</p>
<ul>
<li><input checked="" disabled="" type="checkbox"> Drop Node 16 support</li>
<li><input disabled="" type="checkbox"> Migrate config to <code>app.config.js</code></li>
</ul>
<table>
<thead>
<tr>
<th>Setting</th>
<th align="center">Default</th>
<th>Notes</th>
</tr>
</thead>
<tbody><tr>
<td><code>timeout</code></td>
<td align="center">30</td>
<td>Seconds</td>
</tr>
<tr>
<td><code>retries</code></td>
<td align="center">3</td>
<td><del>5</del> reduced</td>
</tr>
</tbody></table>
<pre><code class="language-js">export default { timeout: 30 };
</code></pre>
The colon on both sides of :-------: centers the column, which marked writes as align="center" on each cell. Task list items become disabled checkboxes. The code block gets class="language-js" but no colors. The heading has no id, so if you need in-page anchor links, add the IDs yourself.
Markdown mistakes that change the output
Missing space after #
#No space is a paragraph that starts with a hash sign, not a heading. CommonMark and GitHub both require a space: # Title.
Mixed list markers
Switching between -, *, and + in the middle of a list starts a new list. * a followed by + b produces two separate <ul> elements, which usually shows up as extra spacing. Pick one marker per list.
Markdown inside HTML blocks
Raw HTML is passed through, but Markdown inside a block-level HTML element is not processed. In <div>, a line reading **not bold**, then </div>, the asterisks stay as literal text. Leave a blank line after the opening tag and before the closing tag if you need Markdown inside.
Front matter
Files from Jekyll, Hugo, or Astro often start with a YAML block between two --- lines. marked does not recognize it: the first --- becomes an <hr>, and the second turns the YAML lines into an <h2> heading. Remove the front matter before converting.
Footnotes
[^1] footnote syntax is not supported. marked reads the definition line as a link reference, so the definition disappears and the marker turns into a link whose address is the footnote text. Rewrite footnotes as ordinary links or a numbered notes section.
The output is not sanitized
marked copies raw HTML from the input into the output, including <script> tags and event handler attributes, and it keeps links such as [x](javascript:alert(1)). For your own content that is expected behavior. If you convert Markdown written by other people, such as comments or user profiles, run the HTML through a sanitizer like DOMPurify before displaying it, or you open your site to cross-site scripting.
When to use a different tool
- To convert existing HTML back into Markdown, use HTML to Markdown.
- To see the converted HTML rendered and style it with CSS, paste it into the HTML Editor.
- To indent the output for easier reading, run it through the HTML Beautifier.
Frequently asked questions
Does this converter support GitHub Flavored Markdown?
Mostly. It uses marked with its GitHub Flavored Markdown option on, so tables, task lists, strikethrough with double tildes, fenced code blocks, and bare URLs that turn into links all work. Footnotes are not supported, and headings are output without id attributes, so there are no automatic anchor links like the ones GitHub adds.
Why does a single line break not start a new line?
In standard Markdown, a single line break inside a paragraph is treated as a space. The converter follows that rule. To force a line break, end the line with two spaces or a backslash, or leave a blank line to start a new paragraph.
Is the generated HTML safe to put on my website?
Only if you trust the Markdown. Raw HTML in the input, including script tags, is copied into the output unchanged, and links to javascript: URLs are kept. That is fine for your own documentation, but Markdown written by users must be passed through an HTML sanitizer such as DOMPurify before it is displayed.
Why did my front matter turn into a heading?
The converter does not know about YAML front matter. The opening line of three dashes becomes a horizontal rule, and the closing line of three dashes turns the lines above it into a level 2 heading. Delete the front matter block before converting, or use a static site generator that strips it for you.
Does it add syntax highlighting to code blocks?
No. A fenced block that starts with a language name, for example js, is output as a pre and code pair with class="language-js". That class is what highlighting libraries such as Prism and highlight.js look for, so include one of them on your page to add colors.
Is my Markdown uploaded anywhere?
No. marked runs in your browser. The input is saved in your browser's local storage so it is restored on your next visit, and Clear removes it. Import URL fetches the file directly from your browser.