CORS header checker
Find why CORS blocks a request. Check origins, credentials, OPTIONS status, allowed methods and request headers.
Result
Add your input, then select Check CORS.
How to use it
Paste the page’s origin and the actual response headers. If the browser sent OPTIONS, include its status, requested method, header names and response headers. Try example shows an Authorization header missing from the preflight allowlist.
What to keep in mind
Checks copied headers without requesting your endpoint. Cookie policy, redirects and cached preflights still need checking in the browser. Up to 64 KB per response header block; this is not a security audit.
Clear removes the current input and result.
Catch problems while customers use your app.
Braith reviews sampled app activity for likely failures and friction. Keep your error tracker for exceptions and stack traces.
Connect first. Pay only when you explicitly activate a paid plan.