HTTP Status Code Reference

A 301 is a permanent redirect - browsers and search engines update their references to the new URL. A 302 is temporary - the original URL should still be used for future requests. For SEO, use 301 for permanent moves.

HTTP 418 "I'm a teapot" is an April Fools' joke from RFC 2324 (Hyper Text Coffee Pot Control Protocol). It means the server refuses to brew coffee because it is, permanently, a teapot. It's not used in real APIs but is a beloved developer easter egg.

4xx errors are client-side — the request has an issue (bad syntax, auth needed, not found). 5xx errors are server-side — the client sent a valid request but the server failed to process it (overloaded, misconfigured, upstream timeout). Always investigate 5xx as they indicate problems on your end.

204 means the request succeeded but there's no response body. Used for successful DELETE operations, ping/health-check endpoints, or saving data where no response is needed. The browser stays on the same page when receiving 204 — useful for AJAX save without navigation.

404 means 'not found' — it may come back. 410 means 'gone' — permanently removed and won't return. Use 410 when you want search engines to de-index the URL quickly. Use 404 for resources that may temporarily be unavailable but could reappear. 410 sends a stronger signal to crawlers.

REST APIs most commonly use 200 (OK), 201 (Created), 204 (No Content), 400 (Bad Request), 401 (Unauthorized), 403 (Forbidden), 404 (Not Found), 409 (Conflict), 422 (Unprocessable Entity), and 500 (Internal Server Error).