HTTP Status Codes Reference
Updated September 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.
Verified Capabilities
Covers all standard 1xx-5xx codes with a one-line description each.
Search narrows the list by code number, name, or description text as you type.
Codes are grouped under 1xx-5xx headers, each with a distinct color.
This is a static reference only — it doesn't check any live URL, and there's no click-to-expand extra detail beyond the one-line description shown.
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.
Who uses the HTTP Status Codes?
- Backend developers choosing the correct status code for REST API responses.
- Frontend developers looking up an unfamiliar status code seen in a network tab during debugging.
- 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
Scroll the list — codes are grouped by category (1xx–5xx) with color-coded headers as you go.
Use the search bar to filter by code number or keyword (e.g. "404" or "not found") — the list narrows instantly.
Each code's description is always visible; there's no need to click to expand it.
Bookmark this page for quick reference while building or debugging APIs.
Tips & tricks
- This is a static reference list, not a live checker — to see the actual status code a URL returns, use this site's HTTP Header Checker or Website Speed Test tool instead.
- Search matches the code number, name, and description text all at once, so searching "webdav" surfaces every WebDAV-specific code.
- The color coding (indigo/green/amber/red/dark red) matches the 1xx-5xx category at a glance, even while scrolled past the category header.
- 418 "I'm a Teapot" is real (RFC 2324) but is an April Fools' joke with no practical use — don't build real logic around it.
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 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.
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.
Works with ChatGPT, Claude, Cursor, GitHub Copilot, VS Code, Poe and more — 106+ tools, zero data collection.