HTTP Status Codes

Look up what any HTTP status code means, in plain English.

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1xx Informational

100: Continue; The server got the request headers and the client can send the body.
101: Switching Protocols; The server is switching protocols as requested, for example to WebSocket.
103: Early Hints; Preliminary headers so the browser can start preloading resources before the final response.

2xx Success

200: OK; The request worked and the response contains the result.
201: Created; The request worked and a new resource was created.Tip: APIs usually return the new resource's URL in a Location header.
202: Accepted; The request was accepted for processing, but the work isn't finished yet.
204: No Content; The request worked and there's nothing to send back.
206: Partial Content; Only part of the file was sent, because the client asked for a range (used for video streaming and resumable downloads).

3xx Redirection

301: Moved Permanently; The page has a new permanent address. Browsers and search engines should use the new URL.Tip: Use 301 (or 308) when moving pages so search rankings carry over.
302: Found; The page is temporarily at a different address. Keep using the original URL.
303: See Other; Go to another URL with a GET request — common after submitting a form.
304: Not Modified; The cached copy is still up to date, so nothing new was sent.
307: Temporary Redirect; Temporarily moved; repeat the same request (same method and body) at the new URL.
308: Permanent Redirect; Permanently moved; repeat the same request (same method and body) at the new URL.

4xx Client error

400: Bad Request; The server couldn't understand the request — often malformed JSON or missing fields.
401: Unauthorized; You need to log in or send valid credentials.Tip: Despite the name, this means “unauthenticated”.
402: Payment Required; Reserved for payment flows; some APIs use it when a subscription or credit is needed.
403: Forbidden; The server knows who you are but you're not allowed to access this.
404: Not Found; Nothing exists at this address.Tip: Make sure removed pages return 404 (or 410), not a 200 page that says “not found”.
405: Method Not Allowed; The URL exists but doesn't accept this method (for example POST instead of GET).
406: Not Acceptable; The server can't produce a response in any format the client accepts.
408: Request Timeout; The client took too long to send the request.
409: Conflict; The request conflicts with the current state, such as editing an outdated version.
410: Gone; The resource was deliberately removed and won't come back.
411: Length Required; The server needs a Content-Length header.
412: Precondition Failed; A condition in the request headers (like If-Match) wasn't met.
413: Content Too Large; The request body (often an upload) is bigger than the server allows.
414: URI Too Long; The URL is longer than the server will process.
415: Unsupported Media Type; The server doesn't accept the body's format — check the Content-Type header.
416: Range Not Satisfiable; The requested byte range is outside the file.
418: I'm a teapot; An April Fools' joke from 1998 (RFC 2324). Some services use it playfully.
422: Unprocessable Content; The request is well-formed but the data fails validation.
425: Too Early; The server won't risk processing a request that might be replayed.
426: Upgrade Required; The client must switch to a different protocol, such as a newer TLS version.
428: Precondition Required; The server requires conditional requests to prevent lost updates.
429: Too Many Requests; You've hit a rate limit. Slow down and retry later.Tip: Look for a Retry-After header telling you how long to wait.
431: Request Header Fields Too Large; The headers (often cookies) are too big.
451: Unavailable For Legal Reasons; Access is blocked for legal reasons, such as a court order.

5xx Server error

500: Internal Server Error; Something went wrong on the server. It's not your fault.Tip: Check the server logs for the underlying error.
501: Not Implemented; The server doesn't support the functionality needed.
502: Bad Gateway; A proxy or load balancer got an invalid response from the server behind it.
503: Service Unavailable; The server is overloaded or down for maintenance. Try again later.Tip: Use 503 with Retry-After during planned maintenance so search engines don't drop pages.
504: Gateway Timeout; A proxy didn't get a response from the upstream server in time.
505: HTTP Version Not Supported; The server doesn't support the HTTP version used.
507: Insufficient Storage; The server can't store what's needed to complete the request.
508: Loop Detected; The server found an infinite loop while processing.
511: Network Authentication Required; You need to log in to the network, like a hotel or airport Wi-Fi portal.

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How to use the HTTP Status Codes

Search by number (404) or by word (redirect).
Read the explanation and practical tip.

What does this tool do?

Every web response starts with a three-digit status code. The first digit tells you the class: 1xx information, 2xx success, 3xx redirection, 4xx a problem with the request, and 5xx a problem on the server.

Why use it?

Understand errors from websites and APIs.
Choose the right code when building an API.
Avoid SEO mistakes with redirects and 404s.

SEO tip

Use 301 or 308 for permanent moves, so search engines transfer signals to the new URL, and make sure missing pages return a real 404 — not a “soft 404” page with a 200 status.

Privacy

The calculation happens instantly in your browser. The numbers you enter are not sent to our servers or saved. There's no account to create and nothing to install.

Last reviewed October 4, 2026 by the M2Toolkit team.

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