HTTP Methods

An HTTP method is idempotent when making the same request once or many times leaves the server in the same final state, so it is safe to retry.

PATCH applies a partial modification to a resource, and JSON Patch (RFC 6902) is a standard format for expressing those changes as an ordered array of operations like add, remove, replace, move, copy, and test.

A production REST API returns consistent Problem Details errors with correct status codes, paginates with cursors for deep pages, versions its contract, uses Idempotency-Keys so retried POSTs run once, and negotiates JSON or XML through Accept and Content-Type.

PUT replaces the whole resource so missing fields get cleared, while PATCH changes only the fields you send and everything else stays untouched.

A missing single resource gets 404, a collection with no matches gets 200 with an empty array, and 204 is for intentionally no body like after a DELETE, not for not-found.