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HTTP Status Codes, Every Code Explained

Look up what any HTTP status code means and when to use it.

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Which code should I return?

A page moved permanently301
A page moved temporarily302
A page was deleted and is not coming back410
A page does not exist404
The site is down for maintenance503 with Retry-After
The visitor must sign in401
The visitor is signed in but not allowed403
The visitor sent too many requests429 with Retry-After
A form was submitted and created something201
Something was deleted successfully, with no body204

This is a reference, not a checker. A page in your browser cannot request another domain, so checking a live URL needs your browser's network panel or a command-line request.

About the HTTP Status Code Reference

This is a searchable reference for HTTP status codes, covering the full set with a plain explanation of each: what it means, when a server should return it, how browsers and caches treat it, and what it signals to a search engine.

Search accepts a number or a description, so typing 404 and typing not found both get you there, as does typing redirect to see the whole 3xx family. Each entry includes the practical notes that specifications leave out, such as the fact that 302 does not pass ranking signals the way 301 does, that 410 tells a crawler a page is gone deliberately while 404 leaves it uncertain, and that 503 with a Retry-After header is the correct response during maintenance.

One thing this is not. It cannot check the status of a live URL, because browsers block pages from requesting other domains. Checking a real URL needs a server, a command-line request, or your browser's own network panel, and this page explains how to read what you find there.

How to use the HTTP Status Code Reference

  1. Search by number or meaningType 404, or type not found, or type redirect.
  2. Read the entryMeaning, when to use it, caching behaviour and SEO notes.
  3. Browse by classThe five families are listed separately.
  4. Use the decision guideCommon situations mapped to the code you should return.

Features

  • Every standard status code with a plain explanation
  • Search by number or by description
  • Browse by class from 1xx to 5xx
  • Caching behaviour for each code
  • Notes on what each means for search engines
  • A guide mapping common situations to the right code
  • Includes widely used non-standard codes
  • Works offline once loaded

Who uses this tool

The http status code reference is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

  • Deciding whether to return 404 or 410 for a removed page
  • Understanding an error in your server logs
  • Choosing the right redirect code for a migration
  • Explaining a status code to a colleague
  • Setting the correct response during maintenance

Frequently asked questions

Why can this not check a live URL?

Because a page in your browser cannot request another domain, which browsers block for security. Any online checker that does this runs it on their server. To check a URL yourself, use your browser's network panel or a command-line request.

What is the difference between 301 and 302?

301 says the move is permanent, so browsers and caches remember it and search engines transfer the old address's signals to the new one. 302 says it is temporary, so the original keeps its signals. Using 302 for a permanent migration is a common and costly mistake.

Should a removed page return 404 or 410?

410 means gone deliberately and permanently, and crawlers drop the page faster. 404 means not found, which could be temporary. Use 410 when you know the page is never coming back, and 404 otherwise.

What should I return during maintenance?

503 with a Retry-After header. It tells crawlers the outage is temporary and to come back later. Returning 200 with a maintenance page, or a redirect to one, risks having your real content replaced in the index.

Is 418 real?

It is defined, in an April Fools specification from 1998 about coffee pots, and a number of servers implement it as a joke. It has no legitimate use and is included here because people look it up.

What does 429 mean?

Too many requests: you have hit a rate limit. A well-behaved server includes a Retry-After header saying how long to wait, and a well-behaved client honours it.

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