Can this check CSS variables and modern properties?

Yes, custom properties (--custom-color), flexbox, grid, and modern pseudo-selectors (:has, :where, :is) are fully recognized.

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CSS Validator

Validate CSS syntax, detect missing semicolons, unmatched braces, and invalid properties.

How to Use CSS Validator

1Paste your CSS rules into the editor.
2Review the error summary list with line and column numbers.
3Fix identified issues directly in the editor.
4Copy validated, clean CSS code.

Key Features & Benefits

Unmatched curly brace ({ }) detection
Missing semicolon warnings on multi-line declaration blocks
Unknown or misspelled CSS property alerts
Formatted statistics: total rules, selectors, and declarations

About CSS Validator

Audit CSS stylesheets for syntax errors and common mistakes. Detects unclosed curly braces, missing semicolons, unknown CSS properties, duplicate declarations, and vendor prefix warnings.

Unlike traditional web tools that send your personal data, uploaded photos, or sensitive text to remote cloud servers, our CSS Validator operates strictly inside your client browser sandbox. This guarantees high processing speeds without network throttling, and ensures your data privacy is completely preserved.

Frequently Asked Questions

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Developer Tools100% In-Browser & Private

CSS Validator

Validate CSS syntax, detect missing semicolons, unmatched braces, and invalid properties.

CSS Code Validator

Lint CSS syntax for missing semicolons, unbalanced braces, and unitless dimensions.

Found 2 Syntax Errors

1 style warnings or unit recommendations.

Diagnostics & Line Numbers

[Line 3]Missing terminating semicolon ';' on CSS declaration: "margin: 20px 0"

[Line 5]Invalid hexadecimal color code "#gggggg". Must be valid hex characters [0-9, A-F].

[Line 6]Unitless length specified for "font-size: 16". Did you mean "16px" or "16rem"?

How to Use CSS Validator

1Paste your CSS rules into the editor.
2Review the error summary list with line and column numbers.
3Fix identified issues directly in the editor.
4Copy validated, clean CSS code.

Key Features & Benefits

Unmatched curly brace ({ }) detection
Missing semicolon warnings on multi-line declaration blocks
Unknown or misspelled CSS property alerts
Formatted statistics: total rules, selectors, and declarations

About CSS Validator

Audit CSS stylesheets for syntax errors and common mistakes. Detects unclosed curly braces, missing semicolons, unknown CSS properties, duplicate declarations, and vendor prefix warnings.