HTTP Methods and Status Codes Reference

Last updated: September 22, 2026

networking api-design rest http web-development

HTTP Methods

Safe and idempotent

Safe: no side effects on the server (read-only).

Idempotent: repeating the request produces the same result as a single request, so it’s safe to retry after a network failure.

Method	Semantics	Safe?	Idempotent?	Use For
GET	Retrieve representation	Yes	Yes	Reading data
POST	Create subordinate resource	No	No	Creating resources, non-idempotent operations
PUT	Replace resource	No	Yes	Full updates, idempotent creates
PATCH	Partial update	No	No	Partial updates
DELETE	Remove resource	No	Yes	Deleting resources
HEAD	GET without body	Yes	Yes	Checking existence, metadata
OPTIONS	Describe capabilities	Yes	Yes	CORS preflight, capability discovery

Code	Name	Meaning
200	OK	Request succeeded (GET, PUT, PATCH with response body)
201	Created	Resource created (POST)
202	Accepted	Request accepted for async processing
204	No Content	Success with no response body (DELETE, PUT)

Code	Name	Meaning
400	Bad Request	Invalid syntax or validation failure
401	Unauthorized	Authentication required
403	Forbidden	Authenticated but not authorized
404	Not Found	Resource doesn’t exist
409	Conflict	Request conflicts with current state (duplicate, version mismatch)
422	Unprocessable Entity	Syntax valid but semantic validation failed
429	Too Many Requests	Rate limit exceeded

Code	Name	Meaning
500	Internal Server Error	Unexpected server failure
502	Bad Gateway	Upstream service failure
503	Service Unavailable	Temporary unavailability (overload, maintenance)
504	Gateway Timeout	Upstream service timeout