CSS Validator
Check CSS syntax and pinpoint the exact error.
Processed locally in your browser. Nothing you enter is uploaded or stored.
- Parses with a real CSS parser, so it catches genuine syntax errors, not just "looks odd".
- Points at the exact line and column of the first error.
- Runs in your browser; styles aren't uploaded.
Why this is private
- Processed locally in your browser. Nothing you enter is uploaded or stored.
- Open your browser's DevTools → Network tab while using this tool — you won't see a request carrying your input, because it never leaves your device.
- Nothing you enter is uploaded to a server or shared with us — the processing happens entirely on your device.
Overview
Checks whether a CSS stylesheet is syntactically valid, using a real CSS parser, and reports the exact line and column of the first error.
How to use it
- 1Paste CSS.
- 2Validation runs automatically as you type.
- 3If invalid, the exact error position and reason are shown.
Tips
- A missing closing brace or semicolon is the most common cause — the reported line is often the end of the file even when the real mistake is earlier, so check upward from there too.
Frequently asked questions
What people use it for
Debug a stylesheet a build tool rejectsPaste the file to find the exact unclosed rule or stray character.
Check CSS pasted from a chat, article or AI toolConfirm it's syntactically complete before adding it to your project.
Verify generated or templated CSSCheck output from a preprocessor or CSS-in-JS template actually parses.
Related guides
- How to read JSON with a tree viewerA tree viewer turns a wall of brackets into a structure you can expand, search and copy paths from. Here's how to use one effectively.
- JSON parse errors explained: 'Unexpected token', 'Expected comma or brace', and the restWhat each common JSON error message actually means, the usual cause, and how to find the spot fast using line and column.
- How to format JSON (and actually understand the errors)JSON looks like a JavaScript object but follows stricter rules. Here's what those rules are and how to read the errors when they're broken.
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CSS Validator