HTTP Status Phrase to Code Lookup

About this calculator

Every HTTP status code defined in RFC 9110 (and its predecessors RFC 7231 and RFC 2616) pairs a three-digit numeric code with a standard reason phrase — “200 OK”, “404 Not Found”, “502 Bad Gateway” — and this tool performs the reverse lookup: type the phrase, get the code and its class (1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, 5xx Server Error). It covers the full IANA-registered range, including less common ones like “418 I'm a Teapot” and “429 Too Many Requests”.

Backend developers, API designers and DevOps engineers reach for this when reading a log line or error message that only shows the phrase, when writing API documentation, or when deciding which code class to return from a new endpoint — knowing that a phrase falls in the 4xx range immediately signals a client-side problem rather than a server fault, which changes how monitoring and alerting should treat it.