All tools

Markdown Validator & Linter

Lint your Markdown for broken links, heading hierarchy issues, unclosed code fences, duplicate headings, and style problems. Paste any .md file and see issues highlighted instantly. Live preview included.

Load example:

Markdown input24 lines
Valid

No issues found

Your Markdown looks clean.

Errors

  • Unclosed code fences
  • Empty link URLs [text]()

Warnings

  • Heading hierarchy skips
  • Multiple h1 headings
  • Duplicate headings
  • Empty image alt text
  • TODO / placeholder text
  • Empty link text

Suggestions

  • Bare URLs
  • Lines > 120 characters
  • Inconsistent list markers
  • Heading punctuation
  • Trailing whitespace
  • No headings found

Browse CLAUDE.md rules

Community-contributed rules for Claude Code — documentation standards, code style, and more.

Browse rules

What this validator checks

  • Errors: unclosed code fences, empty link URLs [text]()
  • Warnings: heading hierarchy skips (h1 to h3), multiple h1s, duplicate headings, missing image alt text, TODO placeholders
  • Suggestions: bare URLs, lines over 120 characters, inconsistent list markers, trailing whitespace

Using this to validate CLAUDE.md

CLAUDE.md is a Markdown file read by Claude Code. A well-structured CLAUDE.md uses clear headings, consistent formatting, and no broken references. Run it through this validator before committing to catch common issues.