# Test usage plans for REST APIs in API Gateway
<a name="api-gateway-usage-plan-test-with-postman"></a>

As an example, let's use the PetStore API, which was created in [Tutorial: Create a REST API by importing an example](api-gateway-create-api-from-example.md). Assume that the API is configured to use an API key of `Hiorr45VR...c4GJc`. The following steps describe how to test a usage plan.

**To test your usage plan**
+ Make a `GET` request on the Pets resource (`/pets`), with the `?type=...&page=...` query parameters, of the API (for example, `xbvxlpijch`) in a usage plan:

  ```
  GET /testStage/pets?type=dog&page=1 HTTP/1.1
  x-api-key: Hiorr45VR...c4GJc
  Content-Type: application/x-www-form-urlencoded
  Host: xbvxlpijch.execute-api.ap-southeast-1.amazonaws.com
  X-Amz-Date: 20160803T001845Z
  Authorization: AWS4-HMAC-SHA256 Credential={access_key_ID}/20160803/ap-southeast-1/execute-api/aws4_request, SignedHeaders=content-type;host;x-amz-date;x-api-key, Signature={sigv4_hash}
  ```
**Note**  
You must submit this request to the `execute-api` component of API Gateway and provide the required API key (for example, `Hiorr45VR...c4GJc`) in the required `x-api-key` header.

  The successful response returns a `200 OK` status code and a payload that contains the requested results from the backend. If you forget to set the `x-api-key` header or set it with an incorrect key, you get a `403 Forbidden` response. However, if you didn't configure the method to require an API key, you will likely get a `200 OK` response whether you set the `x-api-key` header correctly or not, and the throttle and quota limits of the usage plan are bypassed. 

  Occasionally, when an internal error occurs where API Gateway is unable to enforce usage plan throttling limits or quotas for the request, API Gateway serves the request without applying the throttling limits or quotas as specified in the usage plan. But, it logs an error message of `Usage Plan check failed due to an internal error` in CloudWatch. You can ignore such occasional errors.