# Set up a gateway response using the API Gateway REST API
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 Before customizing a gateway response using the API Gateway REST API, you must have already created an API and have obtained its identifier. To retrieve the API identifier, you can follow [restapi:gateway-responses](https://docs.aws.amazon.com/apigateway/latest/api/API_GetGatewayResponses.html) link relation and examine the result. 

**To customize a gateway response using the API Gateway REST API**

1. To overwrite an entire [GatewayResponse](https://docs.aws.amazon.com/apigateway/latest/api/API_GatewayResponse.html) instance, call the [gatewayresponse:put](https://docs.aws.amazon.com/apigateway/latest/api/API_PutGatewayResponse.html) action. Specify a desired [responseType](https://docs.aws.amazon.com/apigateway/latest/api/API_GatewayResponse.html#responseType) in the URL path parameter, and supply in the request payload the [statusCode](https://docs.aws.amazon.com/apigateway/latest/api/API_GatewayResponse.html#statusCode), [responseParameters](https://docs.aws.amazon.com/apigateway/latest/api/API_GatewayResponse.html#responseParameters), and [responseTemplates](https://docs.aws.amazon.com/apigateway/latest/api/API_GatewayResponse.html#responseTemplates) mappings.

1. To update part of a `GatewayResponse` instance, call the [gatewayresponse:update](https://docs.aws.amazon.com/apigateway/latest/api/API_UpdateGatewayResponse.html) action. Specify a desired `responseType` in the URL path parameter, and supply in the request payload the individual `GatewayResponse` properties you want—for example, the `responseParameters` or the `responseTemplates` mapping.