HTTP Status Codes

This document provides a full list of HTTP status codes. Each code includes an explanation and a use case for better understanding.

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Table of Contents

1. Informational Responses (100–199)
2. Successful Responses (200–299)
3. Redirection Messages (300–399)
4. Client Error Responses (400–499)
5. Server Error Responses (500–599)

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1. Informational Responses (100–199)

100 Continue

• Description: Indicates that the initial part of a request has been received and the client can continue.
• Example: Client uploads a large file and receives 100 Continue, signaling it to send the remaining data.

101 Switching Protocols

• Description: Server is switching protocols as requested by the client.
• Example: A client requests an upgrade from HTTP to WebSocket for real-time communication.

102 Processing (WebDAV)

• Description: Server is processing a WebDAV request but has not completed it.
• Example: Complex WebDAV request for a file search receives 102 Processing to avoid timeouts.

103 Early Hints

• Description: Used to pre-load resources before the final response is ready.
• Example: Server sends 103 Early Hints to preload CSS and images for a page.

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2. Successful Responses (200–299)

200 OK

• Description: Request was successful, and the response contains the requested data.
• Example: A browser loads a webpage or an API fetch request returns successfully.

201 Created

• Description: Resource was successfully created.
• Example: A new user account created after form submission.

202 Accepted

• Description: Request accepted for processing, but not yet completed.
• Example: Report generation request in a system that processes it in the background.

203 Non-Authoritative Information

• Description: Request successful, but response is from a cached or third-party source.
• Example: Proxy server returns cached content without directly fetching the latest data.

204 No Content

• Description: Request was successful but there is no content to return.
• Example: User updates profile settings, and the server acknowledges without additional data.

205 Reset Content

• Description: Client should reset the view.
• Example: After submitting data, a form resets for new entries.

206 Partial Content

• Description: Partial response for a range request.
• Example: Resuming a paused video or file download from a specific byte range.

207 Multi-Status (WebDAV)

• Description: Conveys multiple status codes for multiple independent operations.
• Example: WebDAV requests return multiple statuses for each sub-operation on files.

208 Already Reported (WebDAV)

• Description: Used to avoid reporting the same resource multiple times.
• Example: WebDAV responses that include previously processed elements.

226 IM Used

• Description: Server fulfilled a GET request with the instance manipulations applied.
• Example: A response indicating a resource has been manipulated (e.g., compressed) before delivery.

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3. Redirection Messages (300–399)

300 Multiple Choices

• Description: Indicates multiple options for the resource.
• Example: User can choose between multiple file formats or language versions.

301 Moved Permanently

• Description: Resource has a new permanent URL.
• Example: Permanently moved page, updating search engines and bookmarks.

302 Found

• Description: Temporary redirect to another resource.
• Example: Redirect to a login page from a protected resource.

303 See Other

• Description: Redirects to a different resource using GET.
• Example: Redirect to a receipt page after submitting a purchase order.

304 Not Modified

• Description: Indicates cached content is up to date.
• Example: Browser cache check for an image returns 304 if unchanged.

305 Use Proxy (Deprecated)

• Description: Requested resource must be accessed through a proxy.
• Example: Deprecated in HTTP/1.1 due to security concerns.

306 (Unused)

• Description: Previously reserved, but not used.

307 Temporary Redirect

• Description: Similar to 302 but method remains the same.
• Example: Temporarily redirects a POST request without changing method.

308 Permanent Redirect

• Description: Similar to 301 but method remains the same.
• Example: API endpoint moved permanently; clients should update the URI.

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4. Client Error Responses (400–499)

400 Bad Request

• Description: The server could not understand the request.
• Example: Malformed JSON payload in an API request.

401 Unauthorized

• Description: Authentication is required but missing or invalid.
• Example: API request without a valid authentication token.

402 Payment Required (Experimental)

• Description: Reserved for future use regarding digital payment.
• Example: Possible future status for subscription services.

403 Forbidden

• Description: Client has no access rights to the content.
• Example: Unauthorized user attempts access to an admin-only page.

404 Not Found

• Description: Server cannot find the requested resource.
• Example: Request for a non-existent webpage.

405 Method Not Allowed

• Description: HTTP method is not allowed for the requested resource.
• Example: DELETE request to a read-only endpoint.

406 Not Acceptable

• Description: Content does not match client’s Accept headers.
• Example: Client requests XML, but only JSON is available.

407 Proxy Authentication Required

• Description: Proxy authentication required.
• Example: Request through a corporate proxy without credentials.

408 Request Timeout

• Description: Server timed out waiting for the request.
• Example: Slow internet connection causes a timeout.

409 Conflict

• Description: Request conflicts with server state.
• Example: Concurrent updates to a document in a collaborative app.

410 Gone

• Description: Resource permanently removed.
• Example: Deprecated API endpoint.

411 Length Required

• Description: Content-Length header is missing.
• Example: POST request without specifying content length.

412 Precondition Failed

• Description: Preconditions in headers not met.
• Example: Conditional update request fails due to modified data.

413 Payload Too Large

• Description: Payload exceeds server limits.
• Example: File upload exceeds max upload size.

414 URI Too Long

• Description: URI is too long for the server to process.
• Example: Too many parameters in a GET request.

415 Unsupported Media Type

• Description: Unsupported content format.
• Example: Server receives an unsupported media type, such as .exe for an image upload.

416 Range Not Satisfiable

• Description: Requested range not available.
• Example: Requesting a range beyond file length.

417 Expectation Failed

• Description: Expectation in headers cannot be met.
• Example: Server fails to meet Expect: 100-continue header.

418 I'm a Teapot (RFC 2324)

• Description: April Fools' joke status code.
• Example: For fun, returned by a teapot API as a joke.

421 Misdirected Request

• Description: Request was directed to a server that cannot respond.
• Example: Server configuration issue causing requests to be misdirected.

422 Unprocessable Entity (WebDAV)

• Description: Request is well-formed but has semantic errors.
• Example: Valid JSON payload with invalid data.

423 Locked (WebDAV)

• Description: Resource is locked.
• Example: Editing a locked document returns 423 Locked.

424 Failed Dependency (WebDAV)

• Description: Failed due to dependency on another action.
• Example: Chained requests where one fails, causing others to fail.

425 Too Early

• Description: Indicates request might be replayed.
• Example: When using Early Data in HTTP/2 connections.

426 Upgrade Required

• Description: Client should upgrade to a different protocol.
• Example: Server requires client to upgrade to HTTP/2.

428 Precondition Required

• Description: Requires conditions to prevent conflicts.
• Example: PUT request that includes conditional headers.

429 Too Many Requests

• Description: Rate limit exceeded.
• Example: Frequent API calls triggering rate limits.

431 Request Header Fields Too Large

• Description: Headers too large for the server.
• Example: Long headers like cookies exceeding limits.

451 Unavailable For Legal

Reasons

• Description: Resource restricted for legal reasons.
• Example: Content blocked due to a court order.

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5. Server Error Responses (500–599)

500 Internal Server Error

• Description: General server error.
• Example: Server fails unexpectedly due to a misconfiguration.

501 Not Implemented

• Description: Request method not supported.
• Example: Server doesn’t support PATCH requests.

502 Bad Gateway

• Description: Server received invalid response from upstream.
• Example: Proxy server cannot reach backend server.

503 Service Unavailable

• Description: Server is overloaded or under maintenance.
• Example: Site under maintenance returns 503.

504 Gateway Timeout

• Description: Gateway timed out waiting for a response.
• Example: Proxy fails due to slow backend.

505 HTTP Version Not Supported

• Description: HTTP version is not supported by the server.
• Example: Server rejects requests using outdated HTTP versions.

506 Variant Also Negotiates

• Description: Circular content negotiation detected.
• Example: Negotiation logic loop.

507 Insufficient Storage (WebDAV)

• Description: Not enough storage for request.
• Example: Server unable to upload file due to storage limits.

508 Loop Detected (WebDAV)

• Description: Infinite loop detected during processing.
• Example: Server detects recursion in resource.

510 Not Extended

• Description: Further extensions required.
• Example: Client needs to extend request with additional requirements.

511 Network Authentication Required

• Description: Client must authenticate to access the network.
• Example: Hotel Wi-Fi redirecting to login page.

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Each status code is essential for efficient HTTP communication. By understanding these codes, developers can better handle responses and errors, enhancing application robustness and reliability.