CORS Matrix Sandbox
Interactive simulator for Cross-Origin Resource Sharing. Configure client and server headers to diagnose preflight failures instantly.
1. Client Request
2. Server Config (Headers)
Simulation Diagnostics
- Cannot use wildcard '*' for Access-Control-Allow-Origin when the request includes credentials.
- Header 'authorization' is not allowed by Access-Control-Allow-Headers.
Guide & Insights
CORS Problem Diagnostic Lab
Tired of the "Blocked by CORS policy" error? Our CORS Debugger lets you simulate client requests and server responses to see exactly why a browser is blocking a request and provides immediate fixes.
Preflight Simulation
Automatically identifies if an OPTIONS preflight is needed and shows how the browser evaluates Origins, Methods, and Headers.
One-Click Auto Fix
Paste your failing environment and click "Auto Fix" to generate the perfect cross-origin response configuration.
Credential Security Analysis
Explains the traps of Access-Control-Allow-Credentials and helps avoid security risks from using wildcards with credentials.
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