HTTP Status Codes (1xx–5xx) Complete Reference Guide
Comprehensive quick reference for all standard RFC HTTP status codes, REST API conventions, caching behaviors, and client/server error definitions.
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2xx Success Codes
The action was successfully received, understood, and accepted.
| Syntax / Token | Name / Type | Description | Example / Notes |
|---|---|---|---|
200 OK | Standard Success | Request succeeded. Response body contains requested resource payload. | — |
201 Created | Resource Created | Request succeeded and resulted in creation of a new resource (common in POST/PUT). | — |
202 Accepted | Accepted (Async) | Request accepted for async processing, but processing has not completed. | — |
204 No Content | No Content | Request succeeded but returns no response body (common in DELETE or PUT operations). | — |
206 Partial Content | Partial Content | Server is delivering only part of resource due to Range header (used in video streaming). | — |
3xx Redirection Codes
Further action must be taken by the user agent to fulfill request.
| Syntax / Token | Name / Type | Description | Example / Notes |
|---|---|---|---|
301 Moved Permanently | Permanent Redirect | Resource has permanently moved to new URI. Search engines transfer link equity. | — |
302 Found | Temporary Redirect | Resource temporarily resides under different URI. Search engines retain original URL. | — |
304 Not Modified | Cached Copy Valid | Resource has not changed since conditional request header (If-Modified-Since / ETag). | — |
307 Temporary Redirect | Strict Temporary Redirect | Temporary redirect that guarantees HTTP method (POST stays POST) is preserved. | — |
308 Permanent Redirect | Strict Permanent Redirect | Permanent redirect that guarantees HTTP method is preserved. | — |
4xx Client Error Codes
The request contains bad syntax or cannot be fulfilled by client.
| Syntax / Token | Name / Type | Description | Example / Notes |
|---|---|---|---|
400 Bad Request | Malformed Request | Server cannot process request due to client error (invalid JSON, malformed syntax). | — |
401 Unauthorized | Authentication Required | Client lacks valid authentication credentials (missing or expired token). | — |
403 Forbidden | Permission Denied | Client identity is known, but access rights to the resource are denied. | — |
404 Not Found | Resource Not Found | Origin server did not find a current representation for target resource. | — |
405 Method Not Allowed | Method Not Supported | Request HTTP method (e.g. POST) is not supported for this endpoint. | — |
409 Conflict | State Conflict | Request conflicts with current state of server (e.g. duplicate email in registration). | — |
410 Gone | Permanently Deleted | Resource was intentionally deleted and will not be available again (better than 404 for SEO). | — |
422 Unprocessable Entity | Validation Error | Syntax is correct, but payload failed semantic validation rules (WebDAV / REST standard). | — |
429 Too Many Requests | Rate Limited | User has sent too many requests in a given time window (Rate Limiting). | — |
5xx Server Error Codes
Server failed to fulfill an apparently valid request.
| Syntax / Token | Name / Type | Description | Example / Notes |
|---|---|---|---|
500 Internal Server Error | Server Crash | Generic catch-all error when an unexpected condition occurred on the server. | — |
502 Bad Gateway | Upstream Error | Server received an invalid response from upstream server (e.g. Nginx proxying to Node). | — |
503 Service Unavailable | Overloaded / Maintenance | Server is currently unable to handle request due to temporary overloading or maintenance. | — |
504 Gateway Timeout | Upstream Timeout | Server did not receive timely response from upstream server (e.g. database query hang). | — |
Frequently Asked Questions
Common questions and developer tips regarding http status codes (1xx–5xx) quick reference.
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