HTTP Status Code Reference
Look up any HTTP status code — what it means and when you actually see it.
System verdict
CHECK404 Not Found
The server has no resource at that address.
- Code
- 404
- Name
- Not Found
- Category
- Client error
- When you see it
- A mistyped URL, a deleted page, or a broken link. The server is fine; the page is not.
What this cannot tell you
- A reference table, not a live check. It explains what a code means; it does not tell you why a specific site returned one.
- Status codes are added over time and servers define their own within a class. Verify anything unusual against the current HTTP specification.
How this calculation works
Enter a three-digit code, a class like 4xx, or a word from the name. The tool returns the code’s meaning, its category and the situation you typically see it in. The category is colour-coded: a 2xx reads as success, a 5xx as a server failure.
What the results mean
- 4xx — client error
- The request was the problem: a wrong address, missing authentication, or a refused method. The server is working.
- 5xx — server error
- The server received the request but failed to fulfil it. The problem is on the server side, not yours.
- 3xx — redirection
- The resource is elsewhere. 301 is permanent and passes SEO value; 302 is temporary. 304 is a healthy cache hit.
Frequently asked questions
What is the difference between 401 and 403?
401 Unauthorized means you have not authenticated — the server does not know who you are, or your token expired. 403 Forbidden means it knows who you are and you still are not allowed. The names are confusing: 401 is really about authentication, 403 about permission.
Is a 404 my fault or the site’s?
Neither, exactly — it means the address has no resource behind it. The server is running fine. Usually it is a mistyped URL, a deleted page, or a stale link pointing somewhere that no longer exists.
What does 502 Bad Gateway actually mean?
A server acting as a gateway — a CDN or reverse proxy — got an invalid response from the backend it forwards to. The front door is up; the thing behind it is down or misconfigured. It is the site’s problem to fix, not yours.