🚦 HTTP Status Codes: Full List and What Each One Means

What is the HTTP Status Codes?

An HTTP status code is a short numeric reply that a server sends with every response, in the status line right before the response headers and body. The first digit puts the code into one of five classes, so you can tell at a glance what kind of answer you are getting. 1xx codes are informational, 2xx mean success, 3xx mean a redirect is needed, 4xx mean the client (the request) got something wrong, and 5xx mean the server itself failed. Knowing just the first digit is often enough to point you in the right direction, even before you look up the exact code.

The codes are defined by the Internet standards bodies, most recently in RFC 9110 (which replaced the older RFC 7231 and RFC 2616), and are reused across the whole web. That is why a 404 means the same thing whether it comes from a tiny blog, a bank, or a global API. This shared vocabulary is what lets browsers, caches, search-engine crawlers, and monitoring tools all react sensibly without custom rules for every site. A correct status code is not just cosmetic either: search engines treat a 200, a 301, and a 404 very differently, and a page that returns the wrong code can be indexed, dropped, or ranked incorrectly.

Not every registered code shows up every day. Some, like 100 Continue or 103 Early Hints, are informational and mostly invisible because browsers handle them automatically before the real response arrives. Others are rare but important once you know them, such as 429 Too Many Requests from an API rate limiter, 451 Unavailable For Legal Reasons for content blocked by law, or the joke code 418 I am a teapot, which started as an April Fools RFC and is still formally registered today. The IANA HTTP Status Code Registry is the official source of truth for every code and its assigned name.

The most useful day-to-day skill is matching a symptom to a class before you even open the network tab. A broken link is almost always a 404. A login wall is a 401 or 403. A site that loads but whose API calls fail often shows a 502 or 503, because a gateway or reverse proxy could not reach the real server behind it. Once you know the class, the exact code (and the meaning shown here) tells you whether the fix belongs on your side, such as fixing a URL or refreshing a login token, or on the server side, such as waiting out a maintenance window or fixing a backend crash.

You can see the status code for any page yourself. In a browser, open developer tools, go to the Network tab, reload the page, and click the top request to see its status. From a terminal, run curl -I https://example.com to fetch just the headers, and the first line shows the code. Many codes also come with extra headers that matter as much as the number itself: a 429 or 503 often includes a Retry-After header telling you how long to wait, a 301 or 302 includes a Location header with the new URL, and a 304 Not Modified relies on caching headers like ETag and Last-Modified to tell the browser its cached copy is still good.

When to use it

• Looking up what a code like 404, 403, or 502 means while debugging a failing request.
• Choosing the correct status code to return from your own API or web server (for example 201 after creating a record, or 422 for a validation error).
• Explaining to a teammate or client why a page returns the code it does, and whose side the fix is on.
• Checking redirect behaviour, such as the difference between a permanent 301 and a temporary 302 or 307.
• Working out why an integration suddenly broke, such as a 401 after a token expired or a 429 after hitting a rate limit.
• Teaching or revising the HTTP status code families for an interview, certification, or onboarding a new developer.

How to use the HTTP Status Codes

1. Type a code number, a name, or a keyword into the search box (for example 404, not found, or redirect).
2. Or click a class button (1xx through 5xx) to show only codes in that family.
3. Read the matching codes, grouped by class, each with its official name and a short meaning.
4. Combine search and a class filter to narrow a large family quickly, then clear the box to see everything again.
5. Cross-check the code you found against the reference tables below for the exact fix and whether it is a client-side or server-side issue.

Formula & method

Worked examples

The five HTTP status code classes at a glance

Full list of the HTTP status codes you will meet most often

Commonly confused codes and how they differ

Common mistakes to avoid

• Returning 200 for an error page. A friendly error page that still sends a 200 OK code tells crawlers and tools the page worked. Missing pages should return 404 (or 410 if gone for good) so they are handled correctly.
• Confusing 401 and 403. A 401 means you have not proven who you are, so logging in may help. A 403 means the server knows who you are and still refuses, so more credentials will not change anything.
• Using 302 when you mean 301. A 302 is a temporary redirect, so search engines keep indexing the old URL. For a permanent move use 301 (or 308) so ranking and links transfer to the new address.
• Blaming the client for a 5xx. Any code starting with 5 is a server-side failure. Re-sending the same request rarely helps until the server or its upstream gateway is fixed.
• Ignoring the Retry-After header on 429 and 503. Both codes often include a Retry-After header telling you exactly how long to wait. Retrying immediately in a loop just triggers the rate limiter or maintenance page again.
• Treating every 4xx as "my fault". Most 4xx codes do mean the request needs fixing, but a 404 can also mean the server side deleted or moved a page without a redirect. Check both ends before assuming.

Glossary

Status code

The three-digit number a server returns with every HTTP response to describe the outcome of the request.

Class

The family a code belongs to, set by its first digit: 1, 2, 3, 4, or 5.

Client error

A 4xx code, meaning the request itself was wrong, such as a missing page or bad input.

Server error

A 5xx code, meaning the server failed to handle an otherwise valid request.

Redirect

A 3xx code that tells the client to fetch the resource from a different URL.

Gateway

A server such as a proxy or load balancer that forwards a request to another (upstream) server and relays its response.

Retry-After

A response header, often sent with 429 or 503, that tells the client how many seconds (or a date) to wait before trying again.

Idempotent

A request that produces the same result no matter how many times it is repeated, which matters for deciding when it is safe to retry after an error.

Frequently asked questions