How to use CSS Checker
- Start by adding the CSS you want to check into CSS Checker.
- Watch the output update instantly while you adjust the CSS.
- When it looks right, Copy to save it.
About this tool
There is no server behind CSS Checker. CSS Checker works on your stylesheet locally and returns the result instantly.
Modern CSS syntax is preserved so your selectors and values come back intact. Your input never leaves the page, and no account or install is required.
Frequently asked questions
What does CSS Checker do?
CSS Checker runs entirely on your device: add your input, and it checks it locally in real time.
Is CSS Checker free to use?
Yes — CSS Checker is completely free, with no usage limits.
Where is my data processed by CSS Checker?
Entirely in your browser — CSS Checker keeps your data on your own machine and sends nothing anywhere.
Does CSS Checker support modern CSS syntax?
Yes. CSS Checker handles current CSS in your browser and leaves your selectors and values untouched.
Does CSS Checker work offline?
Once the page has loaded, CSS Checker keeps working with no network connection.