CORS Tester
FreeTest CORS headers and cross-origin request policies
About CORS Tester
Cross-origin errors are one of the most confusing things to debug, because the browser blocks the request and the real cause is hidden in response headers you cannot see in the console. This CORS Tester sends a request to an endpoint and reports the actual CORS headers it returns, so you can tell exactly which origins, methods, and headers the server allows.
Give it a URL and ToolHub by Codaiman inspects the Access-Control-Allow-Origin, allowed methods, allowed headers, and credential settings in the response. It runs free in your browser with no signup, making it fast to confirm whether a frontend on one domain will be permitted to call an API on another, or to pin down why a preflight request is failing.
Common uses
- Diagnosing why a fetch call fails with a CORS error in your frontend
- Confirming an API allows requests from your app's origin
- Checking which HTTP methods a server permits cross-origin
- Verifying whether credentialed requests are allowed
- Validating CORS config after updating a server or proxy
How to use
- 1
Configure options
Set your preferences using the options panel below.
- 2
Click Generate
Click the process button to generate your result instantly.
- 3
Copy or download
Copy the result to clipboard or download it directly to your device.
Why ToolHub?
- Industry-standard algorithms
- No data retention
- OWASP-aligned checks
FAQ
Why does my browser block the request but this tool shows headers?
CORS is enforced by the browser based on the headers the server returns. This tool reads those headers directly so you can see the policy that is causing the block.
Does it test preflight (OPTIONS) requests?
It inspects the CORS response headers an endpoint returns, which is what determines whether a preflight would succeed. Mismatched allowed methods or headers are common failure causes.
What does a wildcard origin mean?
An Access-Control-Allow-Origin of * lets any site call the endpoint. That is fine for public read-only APIs but should not be combined with credentialed requests.
Can I use CORS Tester on mobile?
Yes — ToolHub is fully responsive and works on iPhone, Android, tablets and all modern browsers. No app install needed.