What does a 404 error mean?

A 404 Not Found error means the server cannot find the requested resource. This typically occurs when a URL is mistyped, a page has been deleted or moved without a redirect, or a link points to content that no longer exists. It's one of the most common HTTP client errors encountered on the web.

What is the difference between 500 and 502 errors?

A 500 Internal Server Error indicates a generic server-side problem where the server encountered an unexpected condition. A 502 Bad Gateway error occurs when a server acting as a gateway or proxy received an invalid response from an upstream server. Both are server errors, but 502 specifically relates to proxy/gateway communication issues.

What does HTTP 200 OK mean?

HTTP 200 OK is the standard success response code indicating that the request has succeeded. For GET requests, it means the resource was found and returned. For POST requests, it indicates the action was completed successfully. It's the most common response code for successful HTTP requests.

When should I use 301 vs 302 redirects?

Use 301 (Moved Permanently) when a page has permanently moved to a new URL - this transfers SEO value to the new location. Use 302 (Found) for temporary redirects when the original URL will return in the future. Search engines handle these differently: 301 updates their index, while 302 keeps the original URL indexed.

What causes a 403 Forbidden error?

A 403 Forbidden error means the server understood the request but refuses to authorize it. Common causes include insufficient file permissions, IP blocking, geographic restrictions, authentication required but not provided, or accessing a protected directory. Unlike 401 Unauthorized, authentication won't help with 403.

What is a 503 Service Unavailable error?

A 503 Service Unavailable error indicates the server is temporarily unable to handle the request, usually due to maintenance, overload, or temporary downtime. Unlike 500 errors, 503 implies the issue is temporary and the server may include a Retry-After header indicating when to try again.

How do I use this HTTP status code reference?

Simply search by code number (e.g., 404, 500) or description keywords (e.g., 'not found', 'redirect'). You can also filter by category (1xx through 5xx) to browse related codes. Each entry includes the code number, name, and detailed description of when and why it's used.

http-status

HTTP Status Codes Reference - Complete List

Complete HTTP status code reference with all response codes from 100 to 599. Search by code number or description, filter by category. Understand what 404, 500, 301, and every other HTTP status code means.

Showing 58 of 58 status codes

100Continue

Server received request headers, client should send body

101Switching Protocols

Server is switching to a different protocol

102Processing

Server is processing but no response yet (WebDAV)

103Early Hints

Preload resources while server prepares response

200OK

Request succeeded. Standard response for successful requests

201Created

Request fulfilled, new resource created

202Accepted

Request accepted but not yet processed

203Non-Authoritative Info

Response from third-party copy

204No Content

Request succeeded but no content to return

205Reset Content

Request succeeded, reset the document view

206Partial Content

Partial resource returned (Range header)

207Multi-Status

Multiple status codes (WebDAV)

300Multiple Choices

Multiple options for the resource

301Moved Permanently

Resource permanently moved to new URL

302Found

Resource temporarily at different URL

303See Other

Response found at another URL (GET)

304Not Modified

Resource not modified since last request

307Temporary Redirect

Temporary redirect, keep request method

308Permanent Redirect

Permanent redirect, keep request method

400Bad Request

Server cannot process due to client error

401Unauthorized

Authentication required

402Payment Required

Reserved for future use

403Forbidden

Server refuses to fulfill request

404Not Found

Requested resource not found

405Method Not Allowed

HTTP method not supported for this resource

406Not Acceptable

Cannot generate content matching Accept headers

407Proxy Auth Required

Authentication with proxy required

408Request Timeout

Server timed out waiting for request

409Conflict

Request conflicts with current server state

410Gone

Resource permanently deleted

411Length Required

Content-Length header required

412Precondition Failed

Precondition in headers not met

413Payload Too Large

Request entity too large

414URI Too Long

URI too long for server to process

415Unsupported Media Type

Media type not supported

416Range Not Satisfiable

Range header cannot be satisfied

417Expectation Failed

Expect header cannot be met

418I'm a Teapot

April Fools joke (RFC 2324)

422Unprocessable Entity

Request well-formed but semantically wrong

423Locked

Resource is locked (WebDAV)

424Failed Dependency

Request failed due to previous request failure

425Too Early

Server unwilling to process early data

426Upgrade Required

Client should switch to different protocol

428Precondition Required

Server requires conditional request

429Too Many Requests

Rate limiting - too many requests

431Headers Too Large

Request headers too large

451Unavailable For Legal Reasons

Blocked for legal reasons

500Internal Server Error

Generic server error

501Not Implemented

Server doesn't support request method

502Bad Gateway

Invalid response from upstream server

503Service Unavailable

Server temporarily unavailable

504Gateway Timeout

Upstream server timeout

505HTTP Version Not Supported

HTTP version not supported

506Variant Also Negotiates

Content negotiation error

507Insufficient Storage

Server storage full (WebDAV)

508Loop Detected

Infinite loop detected (WebDAV)

510Not Extended

Further extensions required

511Network Auth Required

Network authentication required

Quick Reference

1xx Informational

Request received

2xx Success

Request succeeded

3xx Redirection

Further action needed

4xx Client Error

Client error

5xx Server Error

Server error

HTTP Status Code Categories

1xx Informational

100 Continue
101 Switching Protocols
102 Processing
103 Early Hints

2xx Success

200 OK
201 Created
204 No Content
206 Partial Content

3xx Redirection

301 Moved Permanently
302 Found
304 Not Modified
307 Temporary Redirect

4xx Client Errors

400 Bad Request
401 Unauthorized
403 Forbidden
404 Not Found

5xx Server Errors

500 Internal Server Error
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout

How to Use This Tool

Search by Code

Enter a status code number (e.g., 404, 500, 301) to find its meaning instantly

Filter by Category

Use category filters (1xx-5xx) to browse informational, success, redirect, client, or server error codes

Read Details

Each code includes its name and description explaining when and why the status is returned

Frequently Asked Questions

HTTP status codes are three-digit numbers returned by web servers to indicate the result of a client's request. They are grouped into five categories: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client errors), and 5xx (server errors). Each code communicates specific information about what happened with the request.

Related Tools