VAST Lint is a free Chrome add-on designed to streamline the process of validating VAST XML ad tags directly within the browser. This tool eliminates the need for external validation by automatically detecting VAST XML on a webpage and highlighting errors, warnings, and informational issues inline. Users can see the severity of issues, along with rule IDs and detailed error messages on hover, which makes troubleshooting more efficient.

Supporting VAST versions 2.0 through 4.2, VAST Lint empowers users with immediate feedback and guidance. Each error is marked with squiggly underlines, and users can access comprehensive documentation for each rule via links to the vastlint website. Built on a fast, spec-accurate VAST validator, all operations are performed locally in the browser, ensuring data privacy.