Markdown Linter / Style Checker
Paste your Markdown to instantly check for style issues: heading hierarchy, missing alt text, bare URLs, code block language tags, trailing whitespace, and more. Free, no signup.
Paste Markdown in the editor to see style feedback.
Markdown Linter & Style Checker
This linter checks your Markdown for common style issues, structural problems, and formatting inconsistencies — the same kinds of things a CI pipeline tool like markdownlint would catch. Paste your document and get instant feedback.
Rules checked
| Rule | Severity | What it checks |
|---|---|---|
heading-hierarchy | error | Heading levels must not skip — H1 → H3 (skipping H2) is flagged |
multiple-h1 | warning | A document should have at most one H1 as the page title |
duplicate-heading | warning | The same heading text appears more than once |
no-language | warning | Fenced code block (```) has no language identifier |
bare-url | warning | A plain URL is not wrapped in [text](url) link syntax |
missing-alt-text | warning | An image has empty alt text — bad for accessibility |
no-hard-tabs | warning | Line is indented with a tab character instead of spaces |
trailing-spaces | warning | Line ends with trailing whitespace |
no-multiple-blanks | warning | More than one consecutive blank line |
line-length | warning | Prose line exceeds 120 characters (code blocks are excluded) |
When to lint your Markdown
- Before committing to a docs repo — many teams run markdownlint in CI to enforce consistent style
- When contributing to open-source — projects often have a linting step in their contributing guide
- Before pasting into a CMS — structural issues (skipped headings, missing alt text) affect SEO and accessibility
- When reviewing others' Markdown — quickly check a document without setting up local tooling
Heading hierarchy explained
Headings should form a logical outline. You can start at any level, but you should not skip levels going down. For example:
- ✓ H1 → H2 → H3 → H2 → H3 (valid — going back up is fine)
- ✗ H1 → H3 (invalid — H2 was skipped)
- ✗ H2 → H4 (invalid — H3 was skipped)
Skipped heading levels confuse screen readers and hurt SEO. Search engines use heading hierarchy to understand document structure.
Related tools
- Markdown Live Editor — write and preview Markdown in real time
- Markdown Diff — compare two Markdown documents side-by-side
- Word Count & Reading Time — analyze your document's length and reading time
- YAML Frontmatter Editor — edit Jekyll, Hugo, or Docusaurus frontmatter