Markdown Linter
Lint markdown style and structure issues
Input Markdown
Lint Report
Markdown Lint Examples
The linter flags style issues: long lines, heading jumps, mixed list markers. Example:
Markdown with common issues
Long line, heading jump (H2 to H3 skipping H1), mixed - and * list markers.
Paste into the editor above to see the lint report. Use Sample to load more.
What Is a Markdown Linter?
Markdown is a lightweight markup language for docs, READMEs, and web content. A linter checks your Markdown for style and structure issues: inconsistent heading levels, missing blank lines, broken links, or formatting that may not render as expected. The CommonMark spec and GitHub Flavored Markdown (GFM) define the syntax.
This tool runs entirely in your browser. Your Markdown is parsed and analyzed locally—nothing is sent to a server. The lint report lists issues by line with severity (Error, Warning, Info). For formatting Markdown, use Markdown Formatter. For validation, use Markdown Validator.
How to Use This Tool
Paste or Upload
Paste your Markdown into the left editor or click Upload to load a .md, .markdown, or .txt file. Use Sample to load example data with common issues.
Review the Lint Report
The right panel shows the lint report with line numbers and descriptions. Fix issues in the left editor; the report updates automatically. Use Copy or Download to save the report.
Fix and Re-lint
Address each issue and re-run. For converting Markdown to HTML, use Markdown to HTML. For a TOC from headings, use Markdown TOC Generator.
When Markdown Linting Helps
Before committing docs to GitHub or publishing to a CMS, linting catches issues that could break rendering or confuse readers. Inconsistent heading hierarchies make TOCs unreliable. Broken reference-style links cause 404s. Running your Markdown through here improves quality before review.
Documentation sites, README files, and blog posts benefit from consistent Markdown. For converting to HTML for web use, use Markdown to HTML. For generating a table of contents from headings, use Markdown TOC Generator. For syntax reference, use Markdown Syntax.
Frequently Asked Questions
Is my data private?
Yes. Linting runs entirely in your browser. No data is sent to any server. You can confirm this by opening your browser's Network tab.
What does it check?
Typical checks include heading consistency, blank lines around blocks, list formatting, link validity, and CommonMark/GFM compliance. The exact rules depend on the implementation.
Linter vs Validator?
A linter focuses on style and best practices. A validator checks syntax correctness. Use both for quality. Try Markdown Validator for validation.
Does it support GFM?
Many linters support GitHub Flavored Markdown (tables, task lists, strikethrough). Check the report for GFM-specific issues.
Can it fix issues automatically?
This tool reports issues; you fix them manually. For formatting (whitespace, line breaks), use Markdown Formatter.
Related Tools
For Markdown syntax, see CommonMark and CommonMark spec. GitHub Flavored Markdown extends it. Markdown Guide offers tutorials.