HTTP Status Code

🔴 4xx Client Error Codes (Your Fault)

Code	Name	Plain Meaning	Typical Cause
400	Bad Request	Your request is broken	Invalid JSON, missing fields, bad data
401	Unauthorized	You’re not authenticated	Missing/expired token, not logged in
402	Payment Required	Payment needed (rare)	Subscription expired, quota exceeded
403	Forbidden	You’re not allowed	Wrong role, no permission
404	Not Found	Resource doesn’t exist	Wrong URL, deleted record
405	Method Not Allowed	HTTP method not supported	Using POST on a GET-only endpoint
408	Request Timeout	Server closed connection because the client didn't send a complete request within the server's time limit	Slow networks, overloaded servers, or HTTP pre-connection issues
409	Conflict	Data conflict	Duplicate record, version mismatch
429	Too Many Requests	You’re sending too many requests	Rate limiting

🟢 2xx Success Codes

Code	Name	Meaning
200	OK	Request successful
201	Created	Resource created
202	Accepted	Request accepted, processing
204	No Content	Success, no response body

🟡 3xx Redirect Codes

Code	Name	Meaning
301	Moved Permanently	URL changed forever
302	Found	Temporary redirect
304	Not Modified	Use cached version

🔵 5xx Server Error Codes (Server’s Fault)

Code	Name	Plain Meaning
500	Internal Server Error	Server crashed or bug
502	Bad Gateway	Invalid upstream response
503	Service Unavailable	Server overloaded or down
504	Gateway Timeout	Upstream server too slow

⚡ Ultra-Short Memory Rules

• 400 → "Your request is wrong"
• 401 → "Who are you?"
• 403 → "I know you, but no"
• 404 → "That doesn’t exist"
• 409 → "That already exists"
• 429 → "Slow down"
• 500 → "Server broke"
• 503 → "Server busy/down"