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NeatUtility

HTTP Status Code Reference

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About this tool, examples & FAQ

Explore the complete standard directory of HTTP response status codes. Search by code or keyword, inspect caching behaviors and RFC 9110 specifications, and export structured JSON data without network latency.

Key facts

Verified capabilities and limits of this utility
Official StandardRFC 9110 (HTTP Semantics) and IANA HTTP Status Code Registry
Status Code Classes1xx (Informational), 2xx (Success), 3xx (Redirection), 4xx (Client Error), 5xx (Server Error)
Maximum Input10 KB
Execution Deadline2 s

How to use

  1. Enter a 3-digit status code (e.g., 404, 500), class (5xx), or keyword (e.g., unauthorized) into the search box.
  2. Leave the input blank to view the full directory of all standard codes.
  3. Filter by specific HTTP range (1xx through 5xx) or toggle vendor/unofficial codes using the options controls.
  4. Click Run (or press Ctrl/Cmd + Enter) to view detailed specifications and caching rules.
  5. Switch to the JSON tab to export the full status code catalog directly into your application.

Example

Look up HTTP 404 Not Found specification

Input

404

Example output

HTTP 404 Not Found
Class:       4xx Client Error
Description: Origin server did not find a current representation for the target resource or refuses to disclose.
Cacheable:   Yes
Standard:    RFC 9110 Section 15.5.5

Edge cases

Cacheability by Default

Certain HTTP response codes (such as 200, 204, 301, 308, 404, and 410) are defined by RFC 9110 as cacheable by default unless overridden by Cache-Control headers.

Temporary vs Permanent Redirects

HTTP 301 and 308 are permanent redirects (cached aggressively), whereas 302 and 307 are temporary. 307 and 308 guarantee that the request method (e.g. POST) is not rewritten to GET.

April Fools' Standards (RFC 2324)

HTTP 418 ('I\'m a teapot') was originally defined as an April Fools' joke in RFC 2324 (HTCPCP) and is officially acknowledged in RFC 9110 as reserved.

How it works

  1. Indexes standard HTTP status codes from the official IANA registry and modern RFC 9110 specifications.
  2. Matches numeric codes, category ranges, and full-text keyword searches instantly in local memory.
  3. Annotates each code with official phrase, category classification, cacheability status, and RFC citation.
  4. Operates entirely offline without triggering external web requests.

Related workflows

Frequently asked questions

What is the difference between 401 Unauthorized and 403 Forbidden?

HTTP 401 indicates that authentication is required and has either failed or not yet been provided. HTTP 403 indicates that the server understands who the user is, but refuses to grant access to the resource.

What is the difference between 301 and 302 redirects?

A 301 redirect means the page has permanently moved to a new URL, and search engines transfer ranking signals to the target. A 302 redirect means the move is only temporary.

Are 5xx errors caused by the client or the server?

5xx status codes indicate that an error occurred on the server side (e.g., database crash, gateway timeout, unhandled exception), even if the client's request was valid.

References