Paste your broken Markdown here and click "Fix Markdown!!" to repair itEnter Invalid Markdown

What is Markdown Fixer?

Heading without a blank line above it. Code fence that never closed. Numbered list that flips back to 1 halfway through. If you have written a README in the last week, you have hit at least one of these. This tool walks the document, finds the structural problems, and rewrites them so a renderer doesn't silently mangle your output. Paste broken Markdown into the left panel and you get a clean version on the right — the words are untouched, only the scaffolding around them gets fixed.

Under the hood the fixer follows the CommonMark spec for the core grammar and layers in GitHub Flavored Markdown rules on top, so tables, task lists, and strikethrough survive the round trip. The kinds of issues it catches map closely to markdownlint's rule set — blank lines around block-level elements, consistent list bullet style, balanced fenced code blocks. If you want the original definition of where this format came from, John Gruber's original Markdown syntax page is still the best short read.

Everything runs in your browser — your text never leaves your machine. If you want a second opinion on the output, you can also paste it into another <a href="https://www.jsontotable.org/markdown-formatter" target="_blank" rel="noopener">online Markdown formatter</a> and compare. Most files come back fixed in well under a second. For pipelines that need machine-grade conversion (Markdown to PDF, DOCX, slides), <a href="https://pandoc.org/MANUAL.html" target="_blank" rel="noopener">Pandoc</a> is the go-to once your source is clean — and that is exactly the state this tool leaves you in.

How to Use the Markdown Fixer

Three steps. Each one uses the actual buttons on this page.

Paste Broken Markdown or Load Sample

Paste your Markdown into the left editor. Click Sample Markdown to load an example with the common breakages — missing blank line before an H2, an unclosed ```js fence, a numbered list that restarts, a table with misaligned pipes.

# Order Processing
```python
def process(order):
| Stage | Owner |
|-------|-------
[doc][missing-ref

The fixer reshapes blank-line spacing, closes dangling fenced code blocks, normalises list indentation, and balances inline emphasis per the CommonMark spec.

Click Fix Markdown!!

Hit the green Fix Markdown!! button in the toolbar. The fixer parses the document and rewrites the structural problems. A loading indicator appears while it works. Both panels use syntax highlighting so you can scan the diff visually.

Review Fixed Output

The right panel shows the cleaned Markdown. Your prose, your headings, your code samples — all unchanged. Only the spacing, fences, and indentation are rewritten. Copy the output into your README, your docs site, or your blog post.

When You'd Actually Use This

README Cleanup

Run a project README through the fixer before committing. GitHub renders Markdown strictly, and a single unclosed fence can swallow half your file. The fixer catches exactly the kinds of structural breakages that GitHub's renderer cares about.

Cleaning Up Pasted Content

Copying from Notion, Confluence, or a chat thread into a Markdown file usually leaves you with mangled bullets and stray non-breaking spaces. The fixer flattens those back to plain CommonMark.

Static Site Generators

Hugo, Jekyll, Astro, MkDocs — all of them choke on the same handful of structural mistakes. Fix the source once and your build pipeline stops complaining. The cleaned output also feeds straight into Pandoc if you need to convert to PDF or DOCX afterwards.

Cleaning AI-Generated Markdown

LLMs love to forget the closing ``` on a code fence or jump straight from H2 to H4. The fixer normalises the heading ladder and re-balances fences so what you paste into your docs actually renders.

Common Questions

Is my Markdown stored or sent anywhere?

No. The fixer runs entirely in your browser — there is no server round trip. Your text never leaves the tab.

What kinds of problems does it actually fix?

Missing blank lines around headings and lists, unclosed fenced code blocks, mixed bullet markers (*/-/+) inside one list, broken numbered-list sequences, mismatched emphasis (a stray `*` or `_`), reference-style links that point at undefined labels, and table rows where the pipe count drifts.

Will it change my words?

No. The fixer only touches structural whitespace, fence markers, list bullets, and link syntax. The text content of paragraphs, headings, and code blocks is preserved exactly.

CommonMark or GitHub Flavored Markdown?

Both. The base grammar follows CommonMark; the GFM extensions (tables, task lists, autolinks, strikethrough) are kept intact when present.

Can I use it for large Markdown files?

Up to 64 KB — that covers most READMEs and blog posts. If you have a 200-page handbook, split it by chapter and run each one through.

Is the fixed Markdown always valid?

For the common breakages, yes. For unusual edge cases (deeply nested HTML inside Markdown, custom directive syntax) you may want to validate with our Markdown Validator to catch anything style-specific your team enforces.

Other Markdown Tools You Might Need

Fixing is one piece of a Markdown workflow. Here is what tends to come next: