Markdown Checker (Python)
Check Markdown for common problems (unclosed code fences, bad headings, list spacing, trailing whitespace, broken links) and generate a small Python checker script. Offline, fast, and simple.
How to use
Run a quick Markdown sanity check and (optionally) export a Python checker.
- Paste your Markdown into the input box.
- Adjust options (max line length, trailing spaces rule).
- Click Check Markdown to get a report with line numbers.
- Optional: click Generate Python checker to get a runnable script.
FAQ
Does this fully validate Markdown syntax?
No. It checks common, practical problems (fences, spacing, trailing whitespace, incomplete links), not a full Markdown parser.
What does “unclosed code fence” mean?
A fenced block started with ``` or ~~~ but the closing fence wasn’t found, so the rest of the file may render as code.
Why warn about trailing spaces if Markdown uses them for line breaks?
Two trailing spaces can be intentional; the option “Allow exactly 2 trailing spaces” keeps that behavior while warning on other trailing whitespace.
Can it check Markdown links?
It flags incomplete patterns like ]( without a closing ). It does not fetch URLs or verify link targets.
Is this tool offline?
Yes. The checks run locally in your browser and the script generator does not call the network.
How do I use the Python checker output?
Copy it into a file (for example md_check.py), then run python3 md_check.py README.md or pipe content via stdin.
Can I use this in a pre-commit workflow?
Yes. Use the generated Python script (or port the logic) and fail the commit when it prints any ERROR issues.
Continue your workflow
Browse related tools by task. Use the improved core tools for a consistent workspace with file import, downloads and clear validation errors.