Amazon Cognito and FusionAuth are two popular customer identity and access management (CIAM) solutions that approach the problem from different perspectives. Both solutions provide secure registration, login, and user data management capabilities, as well as support for OAuth tokens and API key management. However, they differ in their design goals, pricing models, and features. Cognito is part of Amazon Web Services and provides a registration and login tool that connects user data to the wider Amazon data processing and advertising network. FusionAuth, on the other hand, offers a full-service platform that gives customers control over their users and data, with a focus on single-tenant security, free pricing for unlimited users, and customization options. Additionally, FusionAuth provides features such as localization, configurable password hashing, reporting and analytics, enterprise identity unification, and customization, making it a more flexible and secure solution for businesses.