HTTP Status Code Reference
Searchable reference for all HTTP status codes. Covers 1xx–5xx classes with descriptions, common use-cases, and which methods typically return each code.
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What is HTTP Status Code Reference?
HTTP status codes are three-digit numbers returned by a web server to describe the outcome of a client's request. They are grouped into five classes: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client error), and 5xx (server error). This reference covers all standardised codes defined in RFC 9110 and its predecessors, with plain-English descriptions, common causes, and notes on which HTTP methods typically produce each code.
How to use this tool
- 1 Use the search box to look up a specific code number (e.g. '429') or keyword (e.g. 'not found').
- 2 Filter by class using the category buttons: 1xx, 2xx, 3xx, 4xx, or 5xx.
- 3 Click any code card to expand it and see a detailed description, common causes, and usage notes.
- 4 Use the class overview at the top to understand the meaning of a category before drilling into specific codes.
When would you use this?
- Debugging an API integration where a third-party service is returning an unexpected status code and you need to understand what it means.
- Designing a REST API and deciding which status codes to return for specific error conditions — for example, 409 Conflict vs 422 Unprocessable Entity.
- Reviewing server logs to understand the distribution of response codes and identify patterns like high 5xx rates or unexpected 3xx chains.
How HTTP Status Code Reference works
HTTP status codes are issued by a server in response to a client's request. They are grouped into five classes by their first digit: 1xx informational, 2xx success, 3xx redirection, 4xx client error, and 5xx server error. This reference covers all codes in RFC 9110 and beyond, with plain-English descriptions and practical notes for API developers.
- 1
Filter by class
Click 1xx, 2xx, 3xx, 4xx, or 5xx to narrow the list to a specific response class. This is useful when you know roughly what kind of response you're handling but want to choose the most semantically appropriate code.
- 2
Search by code, name, or keyword
Type in the search box to filter by code number (e.g. "404"), name (e.g. "redirect"), or any word in the description (e.g. "cache", "rate limit", "auth"). Combine with the class filter for precise results.
- 3
Read the description and RFC reference
Each card shows the code, its official name, a plain-English description of when to use it, and the RFC that defines it. The "Common methods" line shows which HTTP verbs typically return that code.
This is a fully static, offline-capable reference. All data is bundled into the page — no network requests are made when searching or filtering.
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