Why use API Header Inspector?
Debugging APIs often starts with headers: auth schemes, cache directives, tracing IDs, and content negotiation. Enter a URL to fetch it from the browser, list response headers in a stable order, and review timing so you can compare environments without sharing secrets in chat.
Practical tips
- Send custom headers when testing feature flags or alternate auth flows.
- If you only need CORS semantics, pair results with the dedicated CORS Checker.
- Watch for duplicate headers—some proxies concatenate values in non-obvious ways.
Common questions
- Why do I see fewer headers than in curl?
- Browsers enforce CORS and may hide forbidden response headers from JavaScript. The CORS proxy can change what is visible.
- Can I inspect request headers I sent?
- Yes—review the captured request section after the fetch completes to confirm what left the browser.