How it works
Searching the list
Type a number, a name such as Not Found, or a few words of the meaning, and the list narrows as you type. The class buttons keep only 1xx informational, 2xx success, 3xx redirection, 4xx client error or 5xx server error codes.
Pressing a code opens its details: a plain-language meaning, the RFC and section that define it, and a link to that section.
What the details mean
Cacheable by default marks the codes a cache may store without explicit freshness headers, following RFC 9110 section 15.1. Any code can still be made cacheable or not with Cache-Control.
Registry says whether the code is standard, deprecated, or unused (a number the IANA registry reserves but nobody should send). The chart at the foot draws every code; the ones matching your search are filled in ink.
