How can you share user authentication without code duplication across independent applications?

Creating a shared "Users" application for authentication and authorization is an effective way to share user authentication across independent applications without duplicating code. This approach centralizes the logic related to user management and creates a single point of truth for handling authentication, which reduces redundancy.

By designing a separate application dedicated to user authentication and authorization, you ensure that any updates or changes to authentication mechanisms or user management logic need to be made only once. This not only simplifies maintenance but also ensures consistent behavior across all applications that utilize this shared service. Furthermore, using a shared application can enhance security, as it allows for uniform implementation of best practices and security measures in one location.

This comparison shows that while storing user credentials in a shared database or using a third-party authentication service can also facilitate authentication sharing, they don't encapsulate the logic and user management functionalities as effectively as a dedicated shared application does. Implementing authentication separately in each application leads to redundancy and potential inconsistencies, which is why that approach is less effective.