HTTP Status Codes Reference

About HTTP Status Codes

HTTP status codes are three-digit numbers returned by web servers to indicate the result of a client's request. They're essential for debugging APIs, understanding web behavior, and building robust applications.

Status Code Categories

• 1xx Informational: Request received, continuing process
• 2xx Success: Request successfully received, understood, and accepted
• 3xx Redirection: Further action needed to complete the request
• 4xx Client Error: Request contains bad syntax or cannot be fulfilled
• 5xx Server Error: Server failed to fulfill a valid request

FAQ

What's the difference between 301 and 302 redirects?

301 (Moved Permanently) tells search engines to transfer SEO value to the new URL. 302 (Found/Temporary) says the move is temporary — search engines keep the original URL indexed. Use 301 for permanent URL changes and 302 for temporary redirects.

When should I use 400 vs 422?

400 (Bad Request) means the request syntax is malformed. 422 (Unprocessable Entity) means the syntax is correct but the content is semantically invalid (e.g., valid JSON with an email field that's not a valid email). Use 400 for parse errors, 422 for validation errors.

What does 204 No Content mean?

204 means the request succeeded but there's no response body. Common for DELETE requests, auto-save operations, and PUT/PATCH where the client already has the updated data.