When new users discover your app, or when existing users return to it, their first task is to sign up or sign in. When you integrate Amazon Cognito with your client code, you connect your app to AWS resources that aid authentication and authorization workflows. For example, your app uses the Amazon Cognito API to create new users in your user pool, retrieve user pool tokens, and obtain temporary credentials from your identity pool. To integrate Amazon Cognito with your web or mobile app, use AWS SDKs and libraries.

Although Amazon Cognito offers visual tools such as AWS Management Console integration and the hosted UI, AWS has designed the service to work with your app code. You can only configure certain components of Amazon Cognito with the API or the AWS Command Line Interface. For example, you can only register a user for time-based one-time password (TOTP) multi-factor authentication (MFA) with a process that starts with AssociateSoftwareToken.

https://www.baeldung.com/spring-security-oauth-cognito