Free Online Debugging & Inspection Tools

Debugging tools exist for the moments when something that should work quietly doesn't, and the error message in front of you doesn't say why. This category gathers the inspection tools reached for during exactly those moments: a webhook and request bin that hands you a real URL to point a webhook or API callback at so you can see the raw headers and body it actually sends, a CORS debugger that tests a cross-origin request and tells you which response header is missing instead of leaving you to guess from a one-line browser console error, a JWT decoder that reads a token's header and payload and can verify its signature against a secret or public key, an HTTP status code and header reference for when you need the precise meaning of a status or a header without switching tabs to search for it, and an SSL certificate checker that walks a host's TLS chain and flags an expiry before it takes a production site down. Every one of these tools runs against the real request, response, or certificate you give it, directly in your browser, with nothing captured or logged beyond what a request bin is explicitly built to hold.