2xx Success Codes

200 OK, 201 Created, 204 No Content and friends.

Also known as: 200 OK, 201 Created, 204 No Content, success status codes

Status codes in the 2xx range mean the request succeeded. The specific code says how.

Code	Name	Typical use
200	OK	a normal success; the response body has the result (`GET`, `PUT`, `PATCH`)
201	Created	a new resource was made, usually by `POST`; include a `Location` header pointing at it
202	Accepted	the request was received, but processing happens later (a background job)
204	No Content	success with nothing to return, often for `DELETE` or `PUT`
206	Partial Content	part of a resource, for range requests (video, resumable downloads)

POST /orders HTTP/1.1
...
HTTP/1.1 201 Created
Location: /orders/917
Content-Type: application/json

{"id": 917, "status": "pending"}

DELETE /orders/917
HTTP/1.1 204 No Content

Choosing well

Use 201 for creation, not 200, and return the new resource or its location.
Use 202 for asynchronous work, and tell the client how to check progress (a status URL) (long-running operations).
Don’t send a body with 204. By definition there is none.
Don’t return 200 with an error inside. If it failed, use a 4xx or 5xx code (status codes).
Be consistent across your API, so clients can rely on the codes.

Treat any 2xx as success, not just 200: check for the range (res.ok in fetch) (fetch API). Then look at the specific code and body.