What is HTTP status code?
Also known as: response code, status code.
Last updated: July 2026
- HTTP status code
- An HTTP status code is a three-digit number a server returns to describe the outcome of a request. The first digit sets the class: 1xx informational, 2xx success, 3xx redirection, 4xx client error, and 5xx server error. For example, 200 means OK, 404 means Not Found, and 500 means Internal Server Error.
Look up any HTTP status code (200, 301, 404, 500…) with its meaning and category. Free, instant, searchable reference.
The five classes
1xx (100–199) are informational; 2xx (200–299) mean success — 200 OK, 201 Created; 3xx (300–399) are redirects — 301 permanent, 302 temporary; 4xx (400–499) are client errors — 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 429 Too Many Requests; 5xx (500–599) are server errors — 500, 502 Bad Gateway, 503 Service Unavailable.
Common ones to know
200 (success), 301 (moved permanently — important for SEO), 404 (not found), 429 (rate-limited) and 500/503 (server problems) cover most day-to-day debugging and are the codes worth memorising first.
FAQ
What does a 404 mean?
Not Found — the server couldn't find the requested resource at that URL.
What's the difference between 301 and 302?
301 is a permanent redirect (search engines pass ranking to the new URL); 302 is temporary.