Markdown Linter
Paste your Markdown and get instant, live feedback on headings, lists, code blocks, whitespace and more — every issue pinned to its exact line.
Everything you need to write consistent Markdown
Live linting as you type
Issues appear instantly while you edit — no button presses, no waiting. The report updates with every keystroke.
18 practical rules
Headings, list markers, code fences, trailing whitespace, hard tabs, long lines, bare URLs, duplicate references and more — a focused rule set you can rely on.
Severity levels
Each issue is classified as an error, warning or info so you can tell at a glance what breaks rendering versus what is just a style preference.
Exact line numbers
Every finding is pinned to its exact line, so you can jump straight to the problem instead of hunting through the document.
100% private
All linting runs locally in your browser — your document is never uploaded, with no size limits and no account needed.
Copy the report
Export the full report to your clipboard with one click for sharing, issue trackers, or CI-style documentation.
About Markdown Linter
Markdown Linter is a free in-browser tool that checks Markdown documents against a practical set of style rules. It scans headings, lists, fenced code blocks, whitespace, line length, URLs and link references, flagging each issue with its severity and exact line number. The checks follow common Markdown style conventions — single top-level H1, blank lines around headings and code fences, no trailing whitespace or hard tabs, consistent list markers, fenced code with a language tag, and no bare URLs or duplicate reference definitions. Because the analysis runs locally on your device, there are no uploads, no size limits, and nothing ever leaves your computer.
How to lint your Markdown
Three steps from a messy draft to a clean, consistent document.
Paste or upload your Markdown
Type, paste or upload a .md file into the input pane. Linting starts immediately as you edit.
Review the issues
Each finding shows its severity (error, warning or info), a rule code and the exact line number. Counts are summarized in the issues header.
Fix and share
Fix the highlighted lines in your editor, then copy the report to your clipboard when you want to share or track the results.
Things to know
The linter is heuristic and line-oriented: it flags common issues deterministically but does not parse every Markdown dialect. Lines over 120 characters are flagged unless they contain a URL, and code inside fenced blocks is never linted. A document with a single top-level H1, blank lines around blocks and consistent list markers will typically pass clean.