HTTP Codes and HeadersHTTP status code classes: 1xx to 5xx
The first digit tells you the kind of answer. The registry numbers below come from the IANA HTTP Status Code Registry.
The five classes
| Class | Meaning | Codes registered by IANA | Explained on this site |
|---|---|---|---|
| 1xx | Informational | 5 | none |
| 2xx | Success | 10 | 200, 201, 202, 204, 206 |
| 3xx | Redirection | 9 | 301, 302, 303, 304, 307, 308 |
| 4xx | Client error | 29 | 400, 401, 403, 404, 405, 406, 408, 409, 410, 413, 414, 415, 416, 418, 422, 426, 429, 431, 451 |
| 5xx | Server error | 11 | 500, 501, 502, 503, 504, 505, 511 |
Reading a code quickly
- 1xx: not a final answer. The server says "carry on" (100) or sends early hints (103).
- 2xx: it worked.
- 3xx: go somewhere else, or use your saved copy (304).
- 4xx: the request has a problem: wrong address, no permission, bad data, too many requests.
- 5xx: the server has a problem. The same request may work later.
Who should fix it
A 4xx means the sender should change something before trying again. A 5xx means the same request may succeed later and the site owner should look at the server. Automatic retries make sense for 5xx and for 429 (after waiting), not for most other 4xx.
Codes that are not in the standard
Some companies add their own codes, such as 520 to 530 from content delivery networks, or 499 in some servers. They are not in the IANA registry and their meaning depends on the company that sends them: check their documentation.
Is the text after the number important?
No. The text is a hint for people. Programs use the number only, and HTTP/2 and HTTP/3 do not carry the text at all.
Where is the full list?
On the all status codes page of this site, copied from the IANA registry.
Sources
- IANA HTTP Status Code Registry (iana.org/assignments/http-status-codes), last updated 2025-09-15, read 14 November 2026
Read on 14 November 2026.
This is an independent guide. It is not connected with the IETF, IANA, any browser maker or any company named here. Meanings were checked against the RFC texts on 14 November 2026. Responses shown were recorded on 14 November 2026 from a small test server on the author's own computer.