How to use CORS Tester Online
- Start by adding the text you want to check into CORS Tester Online.
- Adjust the Paste the response headers, Request origin, Request method options to match what you need.
- Watch the output update instantly while you adjust the text.
- When it looks right, Copy to save it.
About this tool
There is no server behind CORS Tester Online. CORS Tester Online is a free HTTP & Security Header Tools utility that runs in your browser, doing its work on the input you provide without a backend.
Because it runs on your device, it is fast and private and works offline once loaded. Your input never leaves the page, and no account or install is required.
Frequently asked questions
How do I use CORS Tester Online?
CORS Tester Online lets you check your input right in the browser using the Paste the response headers, Request origin controls, with the result shown instantly and nothing uploaded.
Do I need an account for CORS Tester Online?
No — CORS Tester Online needs no account, sign-up or installation.
Is my input private in CORS Tester Online?
Yes — your input never leaves your device; CORS Tester Online does all the work in your browser.
Can I use CORS Tester Online without a connection?
Yes — after the first load CORS Tester Online runs entirely offline.