Amazon Cognito is a popular authentication service for apps within AWS, but many developers seek alternatives due to its limitations, complex setup, and cost issues. The guide explores several alternatives, including Descope, Firebase Authentication, Keycloak, Auth0, and Microsoft Entra ID, each offering distinct features and benefits for different use cases. Descope is highlighted for its developer-friendly design, visual workflows, and passwordless options, making it suitable for B2C and B2B applications. Firebase Authentication is noted for its simplicity and integration with other Firebase services, ideal for small teams and early-stage apps. Keycloak offers open-source flexibility with extensive protocol support, while Auth0 provides a user-friendly interface with strong enterprise capabilities, although it may present scaling challenges. Microsoft Entra ID is deeply integrated with Microsoft services, making it suitable for enterprises using Microsoft 365 and Azure. Each alternative is tailored to specific needs, such as ease of use, customization, or enterprise integration, offering better fits for projects that outgrow Cognito.