Website Tools

CSS Validator

Check the stylesheets a page uses for CSS syntax errors.

Not sure what to enter? Try an example: example.com

Free & instant No signup How to use FAQ

Enter a URL to check the page's inline and linked CSS for common syntax problems like unclosed braces or missing semicolons.

What does a CSS validator check?

A CSS validator looks through a page's inline styles and linked stylesheets for syntax problems such as unclosed braces, missing semicolons and invalid properties. Browsers silently skip invalid rules, so these mistakes often show up as layout bugs that are hard to trace.

How to validate a page's CSS

Enter the domain or URL in the box above.
Click Validate CSS.
Review each reported issue and the stylesheet it came from.
Fix syntax errors first; vendor-prefixed properties are usually intentional and safe.

Related checks

To check the page's HTML markup, use the HTML Validator.
To find stylesheets that delay rendering, use the Render-Blocking Resources Checker.

Many CSS warnings come from vendor prefixes or newer features and are safe to ignore; parse errors are the ones that break styles. JustChecker watches the live site so a broken stylesheet deploy does not sit unnoticed.

Frequently Asked Questions

Browsers skip a rule they cannot parse, and a missing closing brace can swallow every rule that follows it. Fixing the first error often fixes several "problems" at once.

It checks the stylesheets the page loads, including those from plugins or CDNs. Errors in third-party files need to be fixed by their authors or overridden in your own CSS.

No. Prefixed properties are intentional browser-specific extensions; they are reported for information, not as mistakes.

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