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JamdeskUtilities
Free · Open source · Client-side

MDX Validator

Check MDX for syntax errors

Validate MDX on every deploy

Jamdesk validates your MDX automatically — no broken docs. Learn more

How to Validate MDX

Paste your MDX content into the editor and validation runs automatically. The validator checks for common issues: unclosed JSX tags, malformed frontmatter, unbalanced curly braces in expressions, and invalid Markdown syntax. Errors appear inline with line numbers and descriptions so you can find and fix problems quickly. The validator uses the same MDX compiler that documentation platforms use, so if your content passes validation here, it will compile correctly in your project.

How validation works

The MDX Validator uses the remark-mdx parser (the same parser used by Next.js, Docusaurus, and other MDX build tools) to check your content. It runs a full parse pass and collects all warnings and errors from the unified pipeline. Each issue includes the exact line number, column position, severity level, and a descriptive message. Validation runs automatically as you type with a 300ms debounce to keep the editor responsive.

Common errors the validator catches

Unclosed JSX tags (e.g., <Callout> without </Callout>), malformed YAML frontmatter (missing closing --- or invalid syntax), unbalanced curly braces in MDX expressions, import statements with incorrect syntax, and components used before being imported. Strict mode filters results to errors only, hiding warnings for a cleaner output.

Validating before deployment

Catching MDX errors before deployment prevents broken documentation pages. Paste your content here to verify it compiles, then commit with confidence. For automated validation across an entire project, consider adding remark-mdx to your CI pipeline — this tool uses the same underlying parser.

Frequently Asked Questions

What errors does the validator catch?
The validator catches JSX syntax errors (unclosed tags, mismatched components), frontmatter issues (invalid YAML), expression errors (unbalanced braces), and Markdown problems (malformed links, broken references).
Does validation run automatically?
Yes. Validation runs as you type with a short debounce delay. You do not need to click a button — errors and warnings appear inline as you edit.
Is this the same as my build-time validator?
The validator uses the standard remark-mdx parser, which is the same parser used by most MDX build tools. If your content validates here, it should compile in your project.
Can I validate multiple files at once?
Currently the validator handles one MDX file at a time. Paste your content into the editor to validate it. Batch validation across a project is better handled by your build toolchain.
Is the MDX Validator free and open source?
Yes. The MDX Validator is free and open source under the Apache 2.0 license. The full source code is on GitHub at github.com/jamdesk/utilities, and there are no ads, accounts, or usage limits.

About this tool

The MDX Validator is free and open source, and runs entirely in your browser. Your input is never uploaded, stored, or logged — you can verify this by opening the network tab in your browser developer tools while the tool runs. The full source code is on GitHub under the Apache 2.0 license, so you can read the code, file issues, or fork the project. There are no ads, no accounts, and no usage limits. Built and maintained by Jamdesk.

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