✓ CSS Validator Extra

Advanced CSS validation with brace balance, property syntax, at-rule, and missing-semicolon checks. Detailed line-number reporting — all in your browser, no upload.

CSS input

About the CSS Validator Extra

This CSS validator runs entirely in your browser. Paste your CSS and click Validate to scan it for common syntax problems. The validator checks for balanced curly braces, balanced parentheses, unclosed string literals, missing semicolons at the end of declarations, malformed property names, and at-rule structure (@media, @import, @keyframes, etc.). Each problem is reported with its line number so you can jump straight to it.

What does it check?

Brace balance — every { must have a matching }, properly nested.
Parenthesis balance — parentheses in values like rgb() or calc() must be balanced.
String literals — quoted strings (used in content: "..." or url("...")) must be closed.
Missing semicolons — declarations should end with a semicolon (the last one in a block is optional but recommended).
Property names — property names should be valid identifiers (letters, digits, hyphens).
At-rules — @media, @import, @keyframes and similar must be followed by a block or statement.

How to use the validator

Paste your CSS into the input box.
Click Validate.
Read the result panel — valid CSS reports success; problems list each issue with its line number.
Fix the issues in your editor and re-validate.

Frequently asked questions

Does it check browser support or vendor prefixes? No. This tool checks syntax only. It does not verify that a property is supported by browsers or that vendor prefixes are present.

Does it support SCSS, LESS, or other preprocessors? No. This validator targets standard CSS. Preprocessor syntax like nesting, variables ($var), or mixins will be flagged.

Is my CSS uploaded? No. All validation happens locally in your browser.