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HTTP Status Codes

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Reference for HTTP status codes (1xx-5xx) with meanings, examples and use cases. Debug API responses faster by looking up 404, 503 and every code.

27 codes
100Informational
Continue
Server has received the request headers; client should proceed with request body.
101Informational
Switching Protocols
Server is switching protocols as requested by Upgrade header.
200Success
OK
Standard response for successful HTTP requests.
201Success
Created
Request fulfilled, new resource created.
202Success
Accepted
Request accepted but not yet processed.
204Success
No Content
Server processed the request, no content to return.
206Success
Partial Content
Server delivering only part of the resource (range request).
301Redirect
Moved Permanently
Resource permanently moved to a new URL.
302Redirect
Found
Resource temporarily found at a different URL.
304Redirect
Not Modified
Resource has not been modified since last request (cache hit).
307Redirect
Temporary Redirect
Like 302 but method must not change.
308Redirect
Permanent Redirect
Like 301 but method must not change.
400Client error
Bad Request
Server cannot process request due to client error (malformed syntax).
401Client error
Unauthorized
Authentication required and has failed or not been provided.
403Client error
Forbidden
Server understood request but refuses to authorize it.
404Client error
Not Found
Requested resource could not be found.
405Client error
Method Not Allowed
Request method not supported for the target resource.
408Client error
Request Timeout
Server timed out waiting for request.
409Client error
Conflict
Request conflicts with current state of the server.
410Client error
Gone
Resource no longer available and will not be available again.
418Client error
I'm a teapot
Server refuses to brew coffee because it is a teapot. (RFC 2324)
422Client error
Unprocessable Entity
Request well-formed but unable to be processed (semantic errors).
429Client error
Too Many Requests
User has sent too many requests in a given time (rate limited).
500Server error
Internal Server Error
Generic server error, no more specific message suitable.
502Server error
Bad Gateway
Server acting as gateway received invalid response from upstream.
503Server error
Service Unavailable
Server temporarily unable to handle request (overloaded / down for maintenance).
504Server error
Gateway Timeout
Upstream server failed to respond in time.

About HTTP Status Codes

HTTP status codes are the three-digit results a server returns for each request, grouped by their first digit into five classes: 1xx informational, 2xx success, 3xx redirection, 4xx client error, and 5xx server error. This tool ships a complete code dictionary: enter codes like 404, 301, or 429 to find the standard name, meaning, class, and common use cases, or search by keyword such as "redirect" or "unauthorized". The tables are bundled in the page and queried entirely in your browser, with no network requests. Tip: Bookmark this tool for quick access during your web development work. All processing happens locally in your browser with no installation required.

How to Use

  1. Open the HTTP Status Codes tool page
  2. Enter or paste your data into the input area
  3. View the real-time results and use the copy button to get the output

Use Cases

  • Debug API responses — Quickly confirm semantics of 422 or 409 to tell a data problem from a conflict.
  • Configure redirects — Distinguish 301 permanent from 302 temporary to avoid hurting SEO link equity.
  • Rate-limit design — Pick 429 Too Many Requests and pair it with a Retry-After header.
  • Error handling — Decide on the frontend whether to retry or prompt based on 4xx vs 5xx classes.
  • Learning & interviews — Systematically memorize standard definitions and applicable boundaries.
  • Proxy config — Check 502 vs 504 semantics to configure gateway timeout and retry logic correctly.
  • Cache tuning — Review 304 and 200 semantics to validate ETag-based caching and conditional requests.

FAQ

Difference between 301 and 308?

Both are permanent redirects, but with 301 a browser may switch POST to GET, while 308 strictly preserves the original method and body. Prefer 308 when form submissions are involved.

How to tell 401 from 403?

401 Unauthorized means not authenticated (missing or invalid credentials, go log in); 403 Forbidden means authenticated but lacking permission, where providing credentials again will not help.

When should I return 404 instead of 200?

Missing resources should return 404 so search engines and clients handle them correctly. Serving a "not found" page with 200 creates a soft 404 that harms indexing.

Is status code 418 real?

418 I'm a teapot comes from the April Fools' RFC 2324 joke and is not an official standard, though many frameworks keep it. Do not rely on it for business semantics in production.

What do 502, 503, and 504 mean?

502 means the gateway got an invalid upstream response, 503 means the service is temporarily unavailable (overload or maintenance), and 504 means the gateway timed out waiting upstream. Check the upstream service and timeout settings accordingly.

Any browser compatibility requirements?

This tool works in all modern browsers (Chrome, Firefox, Edge, Safari). No plugins or extensions required.

Can I use it offline?

After initial load, most features work offline. The core logic runs entirely in your browser with no network dependency.

References

Author: Dennis · Full-Stack Developer · contact@oltool.netLast updated: July 2026
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