Amazon Cognito: how to change the Endpoint in AWS SDK .NET?

There is a way to specify a custom endpoint for virtually every service client of the .NET SDK. Please refer to the SDK documentation.

You can use the ServiceURL property of a configuration object you pass when instantiating a client.

using Amazon.CognitoIdentityProvider;

// ...

var config = new AmazonCognitoIdentityProviderConfig
{ 
    ServiceURL = "https://your-endpoint" 
};

var provider = new AmazonCognitoIdentityProviderClient(config);

This technique works if the endpoint doesn't follow the regular Region endpoint pattern.

If you are using the extensions from Amazon.Extensions.NETCore.Setup, you can specify the endpoint in your global client factory:

var options = new AWSOptions();
options.DefaultClientConfig.ServiceURL = "https://your-endpoint";

// ...

var provider = options.CreateServiceClient<AmazonCognitoIdentityProviderClient>();