HTTP request & header tools
HTTP work means reading headers a server actually sent, reproducing a request from a curl command a teammate pasted into chat, or figuring out why a fetch call fails CORS in the browser but works fine from a script. This page covers header inspection, a request client, redirect tracing, CORS and webhook testing, plus quick references for status codes and User-Agent strings.
The online HTTP header checker, redirect checker, webhook tester and online HTTP client all contact a real server or public URL when you run them, since checking a live response needs a live request. Everything else here — header, cookie and User-Agent parsing, the Cache-Control and cURL converters, and the JWT debugger — reads only the text you paste and runs entirely in your browser.
12 tools
Parse headers and cookies
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HTTP headers parser
Inspect HTTP request and response headers with duplicate preservation
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Cache-Control generator
Build Cache-Control response headers and compare cache lifetimes
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User Agent Parser
Parse OS, device and rendering-engine fields from batch User-Agent header lines
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Cookie parser
Inspect Cookie request and Set-Cookie response headers separately
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HTTP status codes
Look up HTTP status codes with response shapes and first checks
Test live requests and CORS
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Online HTTP client
Send a single HTTP request to any API and inspect its status, headers and body directly
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Online HTTP header checker
Check response headers from a public URL for caching and security
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redirect checker
Trace HTTP redirect chains to see every hop before the destination
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CORS tester
Validate CORS headers against Origin and request method
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Webhook tester
Receive HTTP callbacks at a temporary URL to inspect webhook payloads
HTTP & Request Debugging tools FAQ
curl isn't subject to the same-origin policy, so it never triggers CORS at all; only browser-issued requests are checked against the Origin header. Use the CORS tester here to validate a server's Access-Control headers against a specific origin and method before debugging it live in a browser tab.
Paste the curl command into the cURL converter to generate equivalent Fetch, Axios or Python code, including headers, method and body. It also works in reverse, turning a Fetch or Axios call back into a curl command you can run from a terminal.
A redirect chain is every 3xx hop a request passes through before reaching its final destination, each one adding latency and a chance of an HTTPS-to-HTTP downgrade. The redirect checker traces every hop from a real URL so you can see the full path instead of guessing from a single response.