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HTTP Status Code Lookup
Type a code, a reason phrase or a symptom such as “redirect” or “timeout”, then open the entry for the definition and the practical fix.
Search by symptom, not only by number
You often know the behaviour before you know the code: a browser loops on a login page, an API returns an empty body with a 204, a CDN reports a 520 that no RFC defines. The search matches the reason phrase and the summary text as well as the number, so a symptom is a valid starting point.
Group filters narrow the list to a status class. The first digit is the class — 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error — and the class already tells you which side of the connection is expected to change its behaviour.
What each entry contains
Every entry states the standard meaning, the RFC section where it is defined, whether the response is cacheable and whether a retry is safe, then adds the causes and fixes seen in real logs. Those practical notes are clearly separate from the specification.
Codes that are not in the dataset are either unassigned, vendor-specific or obsolete. If a proxy returns a number you cannot find, treat it as vendor-specific and read that vendor's documentation rather than guessing at the class.
All HTTP status codes, searchable
Every entry links to its full reference page. The search box above filters this list.
Frequently asked questions
What is the difference between 404 and 410?
Both mean the target is not available. 410 states that the condition is likely permanent, while 404 makes no claim about the future; caches and crawlers may treat 410 as a stronger signal to remove a URL.
Is a 200 response always a success?
It means the request succeeded at the HTTP level. The body can still describe an application error, which is why APIs often return the error inside a JSON payload.
Why can I not find a code in this list?
The list covers the common registered codes. Vendor codes, unassigned numbers and obsolete codes are out of scope; check the vendor documentation for those.