How to use CORS Checker
- Paste the text you need to check into the input box.
- Use the Paste the response headers, Request origin, Request method settings to control the result.
- The result is computed live in your browser as you edit the input.
- Finish by choosing Copy to take the output with you.
About this tool
CORS Checker is a static, client-side tool with no backend. CORS Checker is a free HTTP & Security Header Tools utility that runs in your browser, doing its work on the input you provide without a backend.
It is designed to do one job well and stay out of your way. It behaves the same on desktop and mobile, with nothing stored remotely.
Frequently asked questions
What is CORS Checker for?
CORS Checker runs entirely on your device: add your input using the Paste the response headers, Request origin controls, and it checks it locally in real time.
Do I need an account for CORS Checker?
No — CORS Checker needs no account, sign-up or installation.
Is my input private in CORS Checker?
Yes — your input never leaves your device; CORS Checker does all the work in your browser.
Can I use CORS Checker without a connection?
Yes — after the first load CORS Checker runs entirely offline.