 <p>1: Recently Cognito launched User Pools feature. This will enable you to do custom signup/login. See: <a href="https://aws.amazon.com/blogs/aws/new-user-pools-for-amazon-cognito/" rel="nofollow">Your user pools</a></p> <p>2: An identity is a unique identifier for the end user. If you use Cognito sync to store the data, 1 identity can have 20 datasets each of max size 1 MB. You can have as many identities (end users) as you want. You can as well store data in S3 and use Cognito vended temporary and scoped credentials to access to S3 data.</p>