HTTP status codes worth memorizing

2xx succeeded, 3xx go elsewhere, 4xx the caller is wrong, 5xx the server is wrong. These are the ones that come up in real APIs.

#http#api#status

text

200 OK                 Standard success
201 Created            Resource created (return Location)
204 No Content         Success, nothing to send back
301 / 308 Moved        Permanent redirect (308 keeps method)
304 Not Modified       Cache revalidation hit
400 Bad Request        Malformed / failed validation
401 Unauthorized       Not authenticated
403 Forbidden          Authenticated, not allowed
404 Not Found          No such resource
409 Conflict           Version or uniqueness clash
422 Unprocessable      Semantically invalid payload
429 Too Many Requests  Rate limited (see Retry-After)
500 Internal Error     Unhandled server failure
502 / 503 / 504        Upstream down, overloaded, timed out

REST basics

Nouns in the path, verbs in the method. GET must be safe and cacheable, PUT/DELETE idempotent, POST neither.

fetch JSON with error handling

`fetch` only rejects on network failure — a 404 or 500 still resolves. Always check `res.ok` yourself.

HTTP status codes worth memorizing

Related

REST basics

fetch JSON with error handling