Developer Reference

HTTP Status Codes Reference

HTTP status codes reference: complete list of 1xx, 2xx, 3xx, 4xx, and 5xx response codes for web developers. Free and searchable.

HTTP status codes are three-digit responses your browser and APIs send back to indicate the outcome of a request. Understanding these codes is essential for debugging web applications, interpreting API behaviour, and writing resilient client code. This reference covers all official status codes across all classes.

1xx — Informational

Code	Name	Meaning
`100`	Continue	Client should continue with the request body.
`101`	Switching Protocols	Server is switching protocols as requested (e.g. to WebSocket).
`102`	Processing	Server has received the request but no response is available yet (WebDAV).
`103`	Early Hints	Preload hints sent before the final response.

2xx — Success

Code	Name	Meaning
`200`	OK	Standard success response.
`201`	Created	Request succeeded and a new resource was created.
`202`	Accepted	Request accepted for processing, not yet completed.
`204`	No Content	Success, but there is no body to return.
`206`	Partial Content	Server is delivering part of the resource (range request).

3xx — Redirection

Code	Name	Meaning
`301`	Moved Permanently	Resource has permanently moved to a new URL.
`302`	Found	Resource temporarily under a different URL.
`303`	See Other	Get the resource from another URL with GET.
`304`	Not Modified	Cached version is still valid; no body sent.
`307`	Temporary Redirect	Temporary redirect that preserves the HTTP method.
`308`	Permanent Redirect	Permanent redirect that preserves the HTTP method.

4xx — Client Errors

Code	Name	Meaning
`400`	Bad Request	Malformed request syntax or invalid framing.
`401`	Unauthorized	Authentication required or failed.
`403`	Forbidden	Authenticated but not allowed to access.
`404`	Not Found	Resource does not exist at this URL.
`405`	Method Not Allowed	HTTP method not supported for this resource.
`408`	Request Timeout	Server timed out waiting for the request.
`409`	Conflict	Request conflicts with the current server state.
`410`	Gone	Resource permanently removed with no forwarding.
`415`	Unsupported Media Type	Payload format is not supported.
`418`	I'm a teapot	April Fools joke code (RFC 2324); occasionally used.
`422`	Unprocessable Entity	Request understood but semantically invalid.
`429`	Too Many Requests	Rate limit exceeded.

5xx — Server Errors

Code	Name	Meaning
`500`	Internal Server Error	Generic server-side failure.
`501`	Not Implemented	Server does not support the functionality.
`502`	Bad Gateway	Invalid response from an upstream server.
`503`	Service Unavailable	Server overloaded or down for maintenance.
`504`	Gateway Timeout	Upstream server did not respond in time.
`507`	Insufficient Storage	Server cannot store the representation (WebDAV).

How this reference is used

Debugging API integration when your client receives unexpected response codes
Understanding server error logs and determining whether to retry a failed request
Implementing proper error handling in applications based on response code classes
Designing API error responses that follow HTTP standards and are predictable to consumers

Frequently asked questions

What is the difference between 4xx and 5xx status codes?

4xx codes indicate a client-side error (invalid request, missing auth, resource not found), meaning the client should not retry without changes. 5xx codes indicate server-side errors, suggesting the server failed to fulfil a valid request and the client may retry later.

When should I use 301 vs 302 redirects?

Use 301 (Moved Permanently) for permanent URL changes and SEO migrations, as search engines and browsers will cache the redirect. Use 302 (Found) for temporary redirects that may change, ensuring clients re-check the original URL later.

Why do some APIs return 200 with an error message instead of 4xx or 5xx?

Some older APIs return 200 to avoid triggering error handlers, placing error details in the response body instead. This is a poor practice; modern REST APIs should use appropriate status codes to signal failures, enabling proper error handling on clients.