Common HTTP Status Codes

2xx Success

• 200 OK: Standard success.
• 201 Created: Resource created (POST/PUT).
• 204 No Content: Success but no body (DELETE).

3xx Redirection

• 301 Moved Permanently: Update your bookmarks/SEO.
• 304 Not Modified: Cached version is good.

4xx Client Error

• 400 Bad Request: Invalid inputs.
• 401 Unauthorized: Authentication missing/invalid.
• 403 Forbidden: Authenticated but no permission.
• 404 Not Found: Resource doesn’t exist.
• 429 Too Many Requests: Rate limited.

5xx Server Error

• 500 Internal Server Error: Something exploded.
• 502 Bad Gateway: Upstream server failed (Nginx -> Node).
• 503 Service Unavailable: Server overloaded/maintenence.