Status Codes

Every API MUST use the appropriate HTTP Status Codes to communicate the result of a request operation.

Every API designer, implementer and consumer MUST understand the semantic of the HTTP Status Code she is using.

At a minimum everyone MUST be familiar with the semantics of "Common" HTTP Status Codes.

Example

Use Codes 4xx or 5xx to Communicate Errors

The 4xx range concerns errors in the API Consumer/Client side, while 5xx range concerns errors in the upstream/backend service or the API implementation.

A request:

GET /orders/1234 HTTP/1.1
...

resulting in the 200 OK response when the requested resource (as identified by request URI) couldn't be found:

HTTP/1.1 200 OK
Content-Type: application/json
...


{
    "code": "NOT_FOUND_ERR_CODE"
    "message" "Order 1234 wasn't found"
}

is not acceptable.

Instead

HTTP/1.1 404 Not Found
...

should be returned.

Recommended Reading

• How to Think About HTTP Status Codes