We wanted to add user profiles to an existing SaaS app. We wanted all of the things that folks dream of, of course: It should be quick to implement, it should be stable and secure, and it should integrate well with our other services, and it should be extensible. Cognito turned out to be a dream. We used it to build the initial login page (supporting password auth and well as OAuth), and it handled all of that complexity for us very easily. We wanted users to be able to fill out "profile pages," and Cognito came built-in with extensible profile fields that we could populate without needing to add additional services, and we wanted to grant users access to some of our AWS microservices, and this was a very easy configuration in AWS, again without the need for any additional components. Amazon Cognito provided a complete Login and User Profile solution for our SaaS app.