CSS Validator | Validate CSS Syntax & Standards
Validate CSS code against W3C standards with instant error detection. Identifies syntax errors, invalid properties, and malformed rules with exact line and column positions. Fast, private, and runs entirely in your browser.
How to Use This Tool
- 1
Paste or type your CSS code into the input area.
- 2
The tool automatically validates your CSS and highlights errors.
- 3
Review error messages with exact line and column positions.
- 4
Fix errors and re-validate until your CSS is error-free.
- 5
Copy or download the validated CSS.
Use Cases & Examples
Debug CSS Syntax Errors
Quickly identify and fix syntax errors, missing semicolons, unclosed braces, and invalid property values.
Code Quality Assurance
Ensure CSS follows W3C standards before deployment or code review.
Learning CSS
Validate CSS while learning to understand proper syntax and avoid common mistakes.
Pre-Build Validation
Check CSS files for errors before running build tools or deploying to production.
CSS Validation Process
Parses CSS using css-tree library following W3C CSS specifications.
Detects syntax errors: missing semicolons, unclosed braces, invalid selectors, and malformed rules.
Identifies invalid property names and values not recognized by CSS standards.
Provides exact error locations (line and column) for quick debugging.
Frequently Asked Questions
Q.What CSS errors does this tool detect?
A. The tool detects syntax errors (missing semicolons, unclosed braces), invalid property names, malformed values, invalid selectors, and other violations of CSS syntax rules.
Q.Does this validate CSS3 and modern CSS features?
A. Yes. The tool supports CSS3, custom properties (CSS variables), Grid, Flexbox, and other modern CSS features.
Q.Will it check for browser compatibility?
A. No. This tool validates CSS syntax and standards compliance. For browser compatibility, use tools like Autoprefixer or Can I Use.
Q.Can it validate SCSS or LESS?
A. No. This tool validates standard CSS only. SCSS and LESS need to be compiled to CSS first.
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