HTTP Status Code Lookup — All 1xx–5xx Codes Explained

HTTP Status Code Categories

Range	Category	What it means
`1xx`	Informational	Request received; server is continuing the process. Rarely seen by clients.
`2xx`	Success	The request was received, understood, and accepted. Your happy path.
`3xx`	Redirection	Further action is needed to complete the request — usually a redirect to another URL.
`4xx`	Client Error	The request contains bad syntax or cannot be fulfilled. The client needs to fix something.
`5xx`	Server Error	The server failed to fulfil a valid request. Something went wrong on your side.

Code	Name	When to use / what it means
`200`	OK	Standard success. Return with a response body for GET/POST.
`201`	Created	A new resource was created (e.g. POST to create a user). Include a `Location` header.
`204`	No Content	Success, but nothing to return — common for DELETE or PUT.
`301`	Moved Permanently	URL has changed forever. Browsers and crawlers update their records. Use for SEO-friendly redirects.
`304`	Not Modified	Cached version is still valid. Browser uses its cached copy — fast and bandwidth-efficient.
`400`	Bad Request	The client sent invalid data. Return a clear error message explaining what's wrong.
`401`	Unauthorized	Missing or invalid authentication. The client can try again with credentials.
`403`	Forbidden	Authenticated but not allowed. Don't reveal whether the resource exists.
`404`	Not Found	Resource doesn't exist. Can also be used deliberately to avoid revealing restricted resources.
`429`	Too Many Requests	Rate limiting. Include a `Retry-After` header so clients know when to retry.
`500`	Internal Server Error	Unhandled exception. Log it, alert on it, and return a generic message to the client.
`503`	Service Unavailable	Down for maintenance or overloaded. Use with `Retry-After` for planned downtime.