HTTP Status Codes Reference
HTTP status codes are the three-digit numbers a web server returns to tell a client whether a request succeeded, was redirected, or failed. This reference lets you browse and search every standard code from 1xx to 5xx, with a plain-language description, real-world use cases, common headers, and related codes for each one.
It is built for web developers, API developers, QA testers, and system administrators who need to look up a code fast, understand exactly when to return it, and compare codes that are easy to confuse — like 401 versus 403 or 301 versus 302.
How to Use This Reference
Search for a code
Type into the search box to filter instantly. Search by code number (404), by name (redirect), or by a description keyword (proxy) to find every matching code.
Filter by category
Click the tabs — All, 1xx, 2xx, 3xx, 4xx, or 5xx — to show only one group when you know the response type but not the exact code.
Open the details
Click any status code card to expand it and reveal its use cases, common response headers, and related codes. Click a related code to jump straight to it.
Pin your favorites
Tap the bookmark icon on any code to pin it to the top of the page. Pins are saved in your browser, so they stay put across sessions. Use Copy to grab the code and name in one click.
Features
Complete Status Code List
Browse every standard HTTP status code, organized into the five categories from 1xx through 5xx — including rarely seen ones like 103, 418, and 451.
Color-Coded Categories
Each group has its own color — Informational, Success, Redirection, Client Error, and Server Error — so you can spot the response type at a glance.
Instant Search
Filter as you type by code number, status name, or any keyword in the description to find the right code in seconds.
Category Filter Tabs
Switch between All, 1xx, 2xx, 3xx, 4xx, and 5xx tabs to narrow the list to a single response category.
Practical Use Cases
Expand any code to see real-world scenarios that explain when and why a server returns it, helping you pick the right code for your API.
Common Response Headers
Each code lists the response headers typically sent with it, such as Location, Retry-After, or WWW-Authenticate.
Related Codes Navigation
Commonly confused codes are linked together — jump from 401 to 403 or 301 to 302 to compare their differences instantly.
Pin for Quick Access
Bookmark the codes you use most so they always sit at the top of the page. Pins are saved locally — no account needed.
Copy to Clipboard
Copy a status code and its name together in one click, ready to paste into your code, docs, or a bug report.
Frequently Asked Questions
What does HTTP status code 200 mean?
200 OK is the standard success response. It means the request was received, understood, and completed, and the response body contains the requested resource. You will see it for a successful GET, a POST that returns data, or any API call that returns the resource you asked for.
What is the difference between 4xx and 5xx errors?
4xx codes are client errors — the request itself has a problem, such as a bad URL (404), missing authentication (401), or malformed data (400), so retrying the same request without changes will fail again. 5xx codes are server errors — the request was valid but the server failed to fulfill it, as with 500 Internal Server Error or 503 Service Unavailable. With 5xx the fix is usually on the server side.
What does a 404, 500, or 403 status code mean?
404 Not Found means the server cannot find the requested resource — the URL is not recognized. 500 Internal Server Error is a generic message for an unexpected condition on the server, such as an unhandled exception. 403 Forbidden means the server understood the request but refuses to authorize it; unlike 401, re-authenticating will not help because the issue is permissions, not identity.
What is the difference between 401 and 403?
401 Unauthorized means no valid authentication credentials were provided — the client should log in and retry. 403 Forbidden means the client is authenticated but does not have permission to access the resource, so re-authenticating will not change the outcome.
When should I use a 301 vs 302 redirect?
Use 301 Moved Permanently when a resource has permanently moved to a new URL, such as a domain change or URL restructuring — search engines will update their index to the new address. Use 302 Found for a temporary redirect where the original URL should still be used in the future, such as a maintenance page or A/B test.
What does 502 Bad Gateway mean?
502 Bad Gateway means a server acting as a gateway or proxy received an invalid response from the upstream server. It commonly happens when a reverse proxy like Nginx cannot reach the backend application, or when the backend returns a malformed response.
Are my pinned codes saved?
Yes. Pinned codes are stored in your browser's local storage and persist across page refreshes and browser sessions. No account or server connection is needed — and because the data is local, your pins stay private to your device.
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