// what is cors?

Cross-Origin Resource Sharing is a browser security mechanism that controls how resources are shared between different origins (domains, protocols, ports). When a script on example.com tries to fetch api.other.com, the browser checks for CORS headers before allowing it.

// how this works

This tool makes a real HTTP request to your URL with an Origin header and inspects the response headers. CORS headers are highlighted in the output.

// which method?

Use GET for static assets (scripts, fonts, images). Use OPTIONS to test preflight requests for API calls. Use the specific method matching your actual request for other cases.