CSS Validator

Free online CSS validator. Instantly check CSS stylesheets for syntax errors, invalid properties, and browser compatibility issues. No sign-up required.

CSS
CSS Input
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Validation Results

Paste CSS above to validate.

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Frequently Asked Questions

What CSS errors does the validator detect?

It detects invalid property names, malformed values, missing semicolons, unclosed brackets, and other CSS syntax errors.

Does it support CSS3?

Yes. The CSS validator supports CSS3 including flexbox, grid, custom properties (CSS variables), and modern CSS features.