Markdown Validator

Input Markdown

Validation Report

Markdown Validation Examples

Valid Markdown has proper spacing and closed fences. Examples:

Valid Markdown

Valid

Invalid – missing heading space and unclosed code fence

#API needs a space after #. The code block is missing closing \`\`\`.

Invalid

Paste either example into the editor above. Use Sample to load more data.

What Is a Markdown Validator?

Markdown has syntax rules. Unclosed code fences, broken links, malformed tables, or invalid HTML can cause rendering issues. A Markdown validator checks your document and reports common problems. The CommonMark spec defines the syntax.

This tool parses your Markdown and generates a validation report. It runs entirely in your browser. Nothing is sent to a server. For formatting, use the Markdown Formatter. For linting (style rules), use the Markdown Linter.

How to Use This Tool

Paste or Upload Markdown

Copy your Markdown and paste it into the left editor. You can also click Upload to load a .md or .markdown file. The Sample button loads example data.

Check the Validation Report

The right panel shows the report. It lists issues like unclosed fences, broken reference links, malformed tables, or empty headings. Download the report for sharing.

Fix and Revalidate

Fix issues in the input and revalidate. For formatting, use the Markdown Formatter. For converting to HTML, use Markdown to HTML.

When Markdown Validation Helps

When publishing docs, READMEs, or content to GitHub, GitLab, or static sites like Jekyll and Hugo, validation catches issues before they cause broken rendering. The GFM spec defines tables and extensions. Unclosed code blocks or malformed tables can break entire pages. Running your Markdown through here gives you confidence before merge or deploy.

Content from multiple authors or AI-generated Markdown often has subtle errors. Validating here provides a checklist. For style consistency (e.g. heading levels, list formatting), use the Markdown Linter.

Frequently Asked Questions

What does it check?

Common issues: unclosed code fences, broken reference-style links, malformed tables, empty headings, invalid HTML. The validator focuses on syntax and structure, not style.

Validation vs linting?

Validation checks syntax and structure. Linting checks style (e.g. heading hierarchy, line length). Use the Markdown Linter for style rules.

Is my data private?

Yes. Validation runs entirely in your browser. No data is sent to any server.

Does it support GFM?

GitHub Flavored Markdown extensions (tables, task lists, strikethrough) are typically supported. The validator reports issues in both standard and GFM syntax.

Can I validate HTML in Markdown?

Raw HTML in Markdown may be flagged if malformed. The validator focuses on Markdown syntax; complex HTML might need a separate HTML validator.