Lint Markdown for common style issues: trailing whitespace, heading gaps, inconsistent bullets.
Paste Markdown to start linting.
Free Markdown Linter checks a document against the 8 most impactful style rules from the markdownlint rule set — line length, single H1, trailing whitespace, consistent bullets, ATX headings, blank lines around headings and fences, and empty links. Issues are grouped by severity with line numbers, rule codes, and snippets. Every rule has its own toggle.
Privacy: This tool runs entirely in your browser. Your text is never uploaded, logged, or cached. Close the tab and it's gone. Verify in DevTools → Network: zero requests fire.
Style consistency is the difference between a README people trust and one they skim past. Linting shouldn't require installing Node and markdownlint-cli. The linter runs 100% in your browser.
| Input | Output | Typical size | Speed | Login needed |
|---|---|---|---|---|
| Markdown (.md) | Lint report (issues + stats) | Any document size | < 50 ms | No |
Here's what this free tool does in detail — every feature is built to solve real problems, runs entirely in your browser, and is free forever.
Covers the rules that catch 90% of real-world issues: MD013 (max line length), MD025 (single H1), MD009 (no trailing whitespace), MD004 (consistent bullets), MD003 (ATX-only headings), MD022 (blank around headings), MD031 (blank around fenced code), and MD042 (no empty links). Each rule has its own toggle so you can match your project's style.
Inspired by DavidAnson/markdownlint but dependency-free. For auto-fix, pair with the Free Markdown Formatter.
Issues are grouped by severity with color-coded badges. Errors are issues that break rendering. Warnings are style violations that hurt readability. Info is for hints and suggestions. The stats grid at the top shows counts per severity so you can triage quickly.
Every issue shows the exact line number (and column where applicable), the markdownlint rule code (MD013, MD022, etc.), the human-readable message, and a snippet of the offending line. This is everything you need to jump to the issue in your editor and fix it without guessing.
After fixing, re-lint and also run the linter alongside the Free Markdown Word Counter for a full document health check.
Fenced code blocks (```) are tracked and their contents skipped — so code samples with long lines, inconsistent indentation, or anything that looks like a rule violation don't trigger false positives. This matters when you're linting technical docs or README files.
For minifying while preserving structure, try the Free Markdown Minifier.
Drop any .md file into the input.
Errors, warnings, info — each with line number, rule code, and snippet.
Disable rules you don't want enforced. Fix issues and re-lint live.
Ship clean READMEs and docs without running a local CLI.
Catch style issues in blog drafts before publishing.
Enforce a consistent style guide across a docs site with one quick paste.
Spot-check formatting before turning in a paper written in Markdown.
Flag style problems quickly without running a full toolchain.
Yes. Free forever, no account required.
Eight core markdownlint rules — line length, single H1, trailing whitespace, consistent bullets, ATX headings, blank lines around headings and fences, and empty links.
Yes. Each rule has its own toggle.
Yes. Fenced code blocks are tracked and their contents skipped to avoid false positives.
No. Runs 100% in your browser.