HTTP Status Codes

The server has received the request headers and the client should proceed to send the request body.

"100 Continue" — server says "keep going, I'm listening"

The server is switching protocols as requested by the client (e.g., upgrading to WebSocket).

"101" — one protocol becomes another

The server has received and is processing the request, but no response is available yet.

"102" — still chewing, haven't swallowed yet

Used to return some response headers before the final HTTP message, allowing resource preloading.

"103 Early Hints" — the server sends you a shopping list before the store opens

The request was successful. The meaning depends on the HTTP method used.

"200 OK" — everything's fine, here's your data

The request was successful and a new resource was created as a result.

"201 Created" — a new resource was born

The request has been accepted for processing, but the processing has not been completed.

"202 Accepted" — your ticket is in the queue

The server has successfully processed the request but is not returning any content.

"204 No Content" — done, nothing to show

The server is delivering only part of the resource in response to a Range request.

"206 Partial" — only part of the file, just what you asked for

A Multi-Status response conveys information about multiple resources in situations where multiple status codes might be appropriate.

"207 Multi-Status" — here are everyone's individual results

The URL of the requested resource has been changed permanently. The new URL is given in the response.

"301 Moved Permanently" — I've moved and given you my new forwarding address

The URI of the requested resource has been changed temporarily.

"302 Found" — it's temporarily over there

The server is redirecting the user agent to a different resource, as indicated by the Location header.

"303 See Other" — go look at that other page via GET

There is no need to retransmit the requested resources. The client can use cached data.

"304 Not Modified" — nothing changed, use your cache

The server sends this response to direct the client to get the requested resource at another URI with the same method.

"307" — temporary detour, same vehicle (method)

The resource is now permanently located at another URI. Method is preserved unlike 301.

"308" — permanently moved AND method preserved

The server cannot or will not process the request due to something perceived to be a client error.

"400 Bad Request" — you sent gibberish

The request lacks valid authentication credentials for the target resource.

"401 Unauthorized" — show me your ID

The server understood the request but refuses to authorize it.

"403 Forbidden" — I know who you are, but you can't come in

The server cannot find the requested resource. The URL is not recognized.

"404 Not Found" — this page does not exist

The request method is known by the server but is not supported by the target resource.

"405 Method Not Allowed" — you're knocking on the wrong door type

The server would like to shut down this unused connection. Sent when server times out waiting for client.

"408" — you took too long to finish your sentence

The request could not be completed due to a conflict with the current state of the target resource.

"409 Conflict" — two things are fighting over the same space

The target resource is no longer available at the origin server and this condition is likely to be permanent.

"410 Gone" — it existed once, but it's gone forever

The server does not meet one of the preconditions in the request header fields.

"412" — the conditions you set weren't met

The request entity is larger than limits defined by server.

"413 Too Large" — your suitcase is too big for the overhead bin

The URI requested by the client is longer than the server is willing to interpret.

"414 URI Too Long" — your address label is a novel

The media format of the requested data is not supported by the server.

"415 Unsupported Media Type" — I don't speak that language

The request was well-formed but was unable to be followed due to semantic errors.

"422" — grammatically correct but logically wrong

The resource that is being accessed is locked.

"423 Locked" — someone else has checked this out

The method could not be performed on the resource because the requested action depended on another action and that action failed.

"424" — the domino that came before you fell

Indicates that the server is unwilling to risk processing a request that might be replayed.

"425 Too Early" — not yet, the security handshake isn't done

The server refuses to perform the request using the current protocol but might after an upgrade.

"426" — you need a better version to enter

The origin server requires the request to be conditional.

"428" — you need to show conditions before we proceed

The user has sent too many requests in a given amount of time (rate limiting).

"429 Too Many" — slow down, you're flooding us

The server is unwilling to process the request because its header fields are too large.

"431" — your luggage has too many labels on it

The user-agent requested a resource that cannot legally be provided.

"451" — reference to Fahrenheit 451, the book about censorship

The server has encountered a situation it doesn't know how to handle.

"500" — something exploded in the engine room

The request method is not supported by the server and cannot be handled.

"501" — feature not built yet

The server, while acting as a gateway or proxy, received an invalid response from the upstream server.

"502 Bad Gateway" — the middleman got a bad answer

The server is not ready to handle the request. Common causes: maintenance or overload.

"503 Service Unavailable" — closed for maintenance, back soon

The server is acting as a gateway and cannot get a response in time from the upstream server.

"504 Gateway Timeout" — the upstream server went radio silent

The HTTP version used in the request is not supported by the server.

"505" — incompatible versions

The server has an internal configuration error: transparent content negotiation results in a circular reference.

"506" — the signpost points to another signpost

The server is unable to store the representation needed to complete the request.

"507" — the hard drive is full

The server detected an infinite loop while processing the request.

"508" — the snake is eating its own tail

Further extensions to the request are required for the server to fulfill it.

"510" — you need extra plugins installed

The client needs to authenticate to gain network access (captive portal).

"511" — you need to log into the WiFi first

A non-standard code used by nginx to indicate that the client closed the connection before the server answered.

"499" — client hung up mid-sentence (nginx-specific)

Cloudflare-specific. The origin server returned an unexpected response.

"520" — Cloudflare has no idea what your server said

Cloudflare-specific. The origin server refused connections.

"521" — Cloudflare knocked, nobody home

Cloudflare-specific. Cloudflare timed out contacting the origin server.

"522" — Cloudflare waited too long

Cloudflare-specific. Cloudflare established a TCP connection but the origin did not send a response in time.

"524" — Cloudflare waited, origin stayed silent