Glossary
HTTP Message Signatures
In short
RFC 9421: a standard for signing selected components of an HTTP message, carried in Signature and Signature-Input headers. Web Bot Auth is a profile of it. A verifier library for RFC 9421 is the starting point for the checks in the guide. Example: OpenAI tells site owners to verify ChatGPT Cloud browser requests according to RFC 9421.
Definition
RFC 9421: a standard for signing selected components of an HTTP message, carried in Signature and Signature-Input headers. Web Bot Auth is a profile of it.
Sourced example
OpenAI tells site owners to verify ChatGPT Cloud browser requests according to RFC 9421. Source, read 2026-11-04.
How it shows up here
A verifier library for RFC 9421 is the starting point for the checks in the guide.
Previous: HTTP 402 Payment Required. Next: IP range JSON. All 41 terms.
Sources
Last reviewed 2026-11-04