List of All Known HTTP Status Codes (HTTP/1.1, HTTP/2 and HTTP/3) as of 20.12.2020, includes non-standard ones too.

1xx: Informational, 2xx: Success, 3xx: Redirection, 4xx: Client Error, 5xx: Server Error

TL;DR: Most common codes are 200 for OK, 307 for Temporary Redirect, 308 for Permanent Redirect, 403 for Forbidden, 404 for Not Found, 405 for Method Not Allowed, 429 for Rate-Limit thingies, and 500 for generic server errors.

Code Name Comment
100 Continue-
101 Switching Protocols-
102 Processing-
103 Early Hints-
200 OK-
201 Created-
202 Accepted-
203 Non-Authoritative Information-
204 No Content-
205 Reset Content-
206 Partial Content-
207 Multi-Status-
208 Already Reported-
218 This is fineApache
226 IM Used-
300 Multiple Choices-
301 Moved Permanently-
302 FoundHTTP/1.1+
303 See Other-
304 Not Modified-
305 Use Proxy-
306 Switch ProxyDeprecated, Reserved
307 Temporary Redirect-
308 Permanent RedirectPreserves POST data too, unlike 301
400 Bad Request-
401 Unauthorized-
402 Payment Required-
403 Forbidden-
404 Not Found-
405 Method Not Allowed-
406 Not Acceptable-
407 Proxy Authentication Required-
408 Request Timeout-
409 Conflict-
410 Gone-
411 Length Required-
412 Precondition Failed-
413 Payload Too LargeHad a different name in HTTP/1.0
414 URI Too LongHad a different name in HTTP/1.0
415 Unsupported Media Type-
416 Range Not SatisfiableHad a different name in HTTP/1.0
417 Expectation Failed-
418 I'm a teapot-
419 Page Expired-
420 Method Failure-
421 Misdirected Request-
422 Unprocessable Entity-
423 Locked-
424 Failed Dependency-
425 Too Early-
426 Upgrade Required-
428 Precondition Required-
429 Too Many Requests-
430 Request Header Fields Too LargeNon-Standard
431 Request Header Fields Too Large-
440 Login Time-out-
444 No Response-
449 Retry With-
450 Blocked by Windows Parental Controls-
451 Unavailable For Legal Reasons-
494 Request Header Too Large-
495 SSL Certificate Error-
496 SSL Certificate Required-
497 HTTP Request Sent to HTTPS Port-
498 Invalid Token-
499 Token Required-
500 Internal Server Error-
501 Not Implemented-
502 Bad Gateway-
503 Service Unavailable-
504 Gateway Timeout-
505 HTTP Version Not Supported-
506 Variant Also Negotiates-
507 Insufficient Storage-
508 Loop Detected-
509 Bandwidth Limit Exceeded-
510 Not Extended-
511 Network Authentication Required-
520 Web Server Returned an Unknown Error-
521 Web Server Is Down-
522 Connection Timed Out-
523 Origin Is Unreachable-
524 A Timeout Occurred-
525 SSL Handshake Failed-
526 Invalid SSL Certificate-
527 Railgun Error-
528 Unknown ErrorUnknown
529 Site is overloaded-
530 Site is frozen-
598 Network read timeout error-