Is there a way to use Basic authentication rather than AWS4-HMAC-SHA256 authentication with the AWS API Gateway Service? I need to support a system that only supports webhook calls with Basic Authentication.
You just need to modify the 401 Unauthorized response template so that it contains the WWW-Authenticate header set to 'Basic'. Apart from that, you'll need to create a custom authorizer that verifies that the provided credentials are correct. You can find more info here