HTTP Status Codes Reference
Complete reference for all standard HTTP status codes with descriptions, grouped by category.
What is HTTP Status Codes?
An HTTP Status Codes Reference is a comprehensive developer reference tool that explains every HTTP status code — the three-digit numbers that web servers return to indicate the result of an HTTP request. Status codes are fundamental to how the web works: they tell clients (browsers, apps, API consumers) whether a request succeeded, failed, needs redirection, or encountered a server error.
HTTP status codes are grouped into five classes: 1xx (informational), 2xx (success), 3xx (redirection), 4xx (client errors), and 5xx (server errors). While 200 OK and 404 Not Found are universally known, codes like 409 Conflict, 422 Unprocessable Entity, 429 Too Many Requests, 503 Service Unavailable, and 304 Not Modified are less familiar but critically important in API design and web development.
Developers need HTTP status code references when debugging API integrations, designing RESTful APIs, troubleshooting server errors, implementing error handling in client applications, and understanding caching behavior. Choosing the semantically correct status code in an API makes it much easier for clients to handle responses correctly.
How to Use HTTP Status Codes
- 1Step 1: Search for a specific status code by typing the three-digit number into the search field, or browse by category (2xx success, 3xx redirect, 4xx client error, 5xx server error).
- 2Step 2: Read the status code name and short description first to understand the general meaning. Then read the detailed explanation to understand the precise semantics and when to use it.
- 3Step 3: For API design decisions, compare similar codes — for example, understand the difference between 401 Unauthorized vs 403 Forbidden, or 400 Bad Request vs 422 Unprocessable Entity.
- 4Step 4: Check the usage notes for information about which HTTP methods typically use this status code, whether a response body is expected, and any headers commonly included with this status.
- 5Step 5: Use the reference to choose the correct status code for your API endpoints, configure error handling in your client code, or troubleshoot unexpected status codes from third-party services.
Benefits of Using HTTP Status Codes
- ✓Correct API Design: Using semantically correct HTTP status codes makes APIs more intuitive, self-documenting, and easier for client developers to handle correctly without reading extensive documentation.
- ✓Faster Debugging: When an API or web server returns an unexpected status code, the reference immediately explains what the code means and the likely causes, speeding up troubleshooting.
- ✓Client Error Handling: Understanding the full range of status codes enables better client-side error handling with specific responses to 429 Rate Limit, 503 Service Unavailable, and other scenarios.
- ✓Cache Behavior Understanding: 3xx redirect codes, 304 Not Modified, and cache-related headers are critical to understanding browser and CDN caching behavior that affects performance.
- ✓Security Awareness: Knowing when to use 401 vs 403 prevents leaking information about resource existence to unauthorized users — a common security consideration in API design.
- ✓RESTful Best Practices: A comprehensive reference helps developers follow HTTP semantic conventions, making their APIs consistent with web standards and framework expectations.
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About HTTP Status Codes
HTTP Status Codes provides a comprehensive, searchable reference for all standard HTTP status codes from 1xx to 5xx. Each code includes its official name, a plain-English description, and common use cases. Bookmark this tool for quick lookups during API development.
- All 1xx–5xx status codes covered
- Searchable by code or name
- Plain-English descriptions
- Common use cases for each code