HTTP Status Codes Reference
Updated July 2026
Complete HTTP status code reference: 1xx, 2xx, 3xx, 4xx, 5xx codes with descriptions and when to use each. Searchable and filterable — free online guide.
Diagnosing web and network issues quickly is critical for site owners, developers, and SEO professionals. The HTTP Status Codes delivers actionable data in seconds.
Complete HTTP status code reference: 1xx, 2xx, 3xx, 4xx, 5xx codes with descriptions and when to use each. Searchable and filterable — free online guide. Results are immediate — no waiting, no loading screens, no account required.
How to use the HTTP Status Codes
Open the tool, enter your input, and get your result instantly. The interface is designed to be self-explanatory — no tutorial or manual needed. Where options exist, they are clearly labelled with sensible defaults. Your result can be copied to the clipboard or downloaded with a single click.
Tips for the best results
- Results reflect live server data — refresh to get the latest reading.
- Compare results across multiple URLs to identify inconsistencies quickly.
Who uses the HTTP Status Codes?
- Backend developers choosing the correct status code for REST API responses.
- Frontend developers debugging unexpected server responses during API integration.
- Students learning web fundamentals and the HTTP request/response cycle.
Common uses and search terms
The HTTP Status Codes is frequently used for: http status, 404, 200, status codes, http error. Whether you need a quick result or are working through a longer project, the tool handles all common variations without any configuration.
Why use Allio Tools's HTTP Status Codes?
Everything runs locally in your browser. No data is sent to a server, logged, or stored anywhere. The tool is completely free with no usage limits, no premium tiers, and no account required. Available in 11 languages and optimised for all screen sizes, the HTTP Status Codes works on desktop, tablet, and mobile with no app download needed.
See also:IP Address Lookup · Website Speed Test · DNS Lookup
How the HTTP Status Codes works
Browse codes by category using the tabs: 1xx (Informational), 2xx (Success), 3xx (Redirection), 4xx (Client Error), 5xx (Server Error).
Use the search bar to find a specific code or keyword (e.g. "404" or "not found").
Click any code to expand its full description, common causes, and implementation notes.
Bookmark this page for quick reference while building or debugging APIs.
Tips & tricks
- Run the HTTP Status Codes before and after making server configuration changes to confirm the update took effect.
- Use the browser's Developer Tools alongside the HTTP Status Codes for a complete picture of network and performance behaviour.
- Results reflect live data — re-run the check after a recent change to verify propagation across DNS caches.
Frequently Asked Questions
What is the difference between 301 and 302 redirects?
301 Moved Permanently tells search engines and browsers the resource has moved forever — they update their index and cache the new URL. 302 Found is a temporary redirect — search engines keep the original URL indexed. Use 301 for permanent URL changes.
What causes a 502 Bad Gateway vs 503 Service Unavailable?
502 means the server received an invalid response from an upstream server (common in reverse proxy setups). 503 means the server is temporarily unable to handle requests (overloaded or in maintenance). Both indicate server-side issues.
When should I use 400 vs 422 for API validation errors?
400 Bad Request is for malformed requests (invalid JSON, missing required headers). 422 Unprocessable Entity is for syntactically valid requests that fail business logic validation (e.g. email already exists). Many REST APIs use 400 for both.
What is the difference between 401 Unauthorized and 403 Forbidden?
401 means the user is not authenticated — they need to log in or provide credentials. 403 means the user IS authenticated but lacks permission to access the resource. Returning 403 reveals the resource exists; returning 404 hides that.
What does HTTP 418 "I'm a Teapot" mean?
HTTP 418 is an April Fools' joke from RFC 2324 (1998) — any attempt to brew coffee with a teapot returns 418. It's a real status code that some frameworks implement as an Easter egg. It has no practical use.
Is the HTTP Status Codes free to use?
Yes, the HTTP Status Codes on Allio Tools is completely free with no sign-up or registration required. It works directly in your browser.
How does the HTTP Status Codes work?
Complete HTTP status code reference: 1xx, 2xx, 3xx, 4xx, 5xx codes with descriptions and when to use each. Searchable and filterable — free online guide. No data is sent to a server — everything runs locally in your browser for maximum privacy and speed.
Do I need to install anything to use the HTTP Status Codes?
No installation needed. The HTTP Status Codes runs entirely in your web browser on any device — desktop, tablet, or mobile.
Is my data safe when using the HTTP Status Codes?
Completely safe. The HTTP Status Codes processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
Does the HTTP Status Codes work offline?
After the page loads for the first time, the HTTP Status Codes works without an internet connection for all client-side processing. Tools that fetch live external data (such as DNS or network lookups) require an active connection.
How current is the data returned by the HTTP Status Codes?
The HTTP Status Codes fetches live data in real time each time you run it. Results reflect the current state of the server or domain at the moment of the request.
Why does the HTTP Status Codes sometimes return different results than other tools?
Results depend on the real-time state of the target server and DNS propagation, which can vary by geographic region and caching TTL. If you see inconsistencies, wait a few minutes and re-test — DNS changes can take up to 48 hours to propagate fully worldwide.
Does the HTTP Status Codes work on all browsers?
Yes. The HTTP Status Codes is built with standard browser APIs and works on all modern browsers including Chrome, Firefox, Safari, and Edge — on both desktop and mobile. No plugins, extensions, or third-party software are required.
How do I save or export my results from the HTTP Status Codes?
Select and copy the result text to paste into any document or app. For image tools, a Download button saves the file directly to your device. Your browser's built-in screenshot function also captures results quickly. No account or login is required.
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