# Call an API with an API Gateway Lambda authorizer
<a name="call-api-with-api-gateway-lambda-authorization"></a>

 Having configured the Lambda authorizer (formerly known as the custom authorizer) and deployed the API, you should test the API with the Lambda authorizer enabled. For this, you need a REST client, such as cURL or [Postman](https://www.postman.com/). For the following examples, we use Postman. 

**Note**  
 When calling an authorizer-enabled method, API Gateway does not log the call to CloudWatch if the required token for the `TOKEN` authorizer is not set, is null, or is invalidated by the specified **Token validation expression**. Similarly, API Gateway does not log the call to CloudWatch if any of the required identity sources for the `REQUEST` authorizer are not set, are null, or are empty.

 In the following, we show how to use Postman to call or test an API with a Lambda `TOKEN` authorizer. The method can be applied to calling an API with a Lambda `REQUEST` authorizer, if you specify the required path, header, or query string parameters explicitly. 

**To call an API with the custom `TOKEN` authorizer**

1.  Open **Postman**, choose the **GET** method, and paste the API's **Invoke URL** into the adjacent URL field. 

    Add the Lambda authorization token header and set the value to `allow`. Choose **Send**.   
![\[Call API with Lambda authorization allow token\]](http://docs.aws.amazon.com/apigateway/latest/developerguide/images/custom-auth-call-api-with-allow-token.png)

    The response shows that the API Gateway Lambda authorizer returns a **200 OK** response and successfully authorizes the call to access the HTTP endpoint (http://httpbin.org/get) integrated with the method. 

1.  Still in Postman, change the Lambda authorization token header value to `deny`. Choose **Send**.   
![\[Call API with Lambda authorization deny token\]](http://docs.aws.amazon.com/apigateway/latest/developerguide/images/custom-auth-call-api-with-deny-token.png)

   The response shows that the API Gateway Lambda authorizer returns a **403 Forbidden** response without authorizing the call to access the HTTP endpoint.

1.  In Postman, change the Lambda authorization token header value to `unauthorized` and choose **Send**.   
![\[Call API with Lambda authorization unauthorized token\]](http://docs.aws.amazon.com/apigateway/latest/developerguide/images/custom-auth-call-api-with-unauthorized-token.png)

    The response shows that API Gateway returns a **401 Unauthorized** response without authorizing the call to access the HTTP endpoint. 

1.  Now, change the Lambda authorization token header value to `fail`. Choose **Send**.   
![\[Call API with Lambda authorization fail token\]](http://docs.aws.amazon.com/apigateway/latest/developerguide/images/custom-auth-call-api-with-fail-token.png)

    The response shows that API Gateway returns a **500 Internal Server Error** response without authorizing the call to access the HTTP endpoint.