HTTP Status Codes Reference
Searchable reference of all common HTTP status codes with descriptions, use cases, and color-coded categories.
Searchable reference of all common HTTP status codes with descriptions, use cases, and color-coded categories.
HTTP status codes are three-digit numbers returned by a web server in response to a request. They indicate whether the request was successful (2xx), redirected (3xx), caused a client error (4xx), or a server error (5xx).
A 401 Unauthorized means the request lacks valid authentication credentials — the user needs to log in. A 403 Forbidden means the server understood the request but the authenticated user does not have permission to access the resource.
A 500 status code indicates an unexpected server-side error. It means the server encountered a condition it could not handle. Common causes include unhandled exceptions, misconfigured servers, or database connection failures.
A 301 is a permanent redirect — search engines transfer SEO value to the new URL. A 302 is a temporary redirect — the original URL retains its SEO value. Use 301 for permanent URL changes and 302 for temporary moves.