This article discusses various SaaS authentication methods and their implementation. It covers email/password authentication, social logins, magic links, MFA (Multi-factor Authentication), and SSO (Single Sign-On). The choice of an authentication method depends on the app's nature, security requirements, user preferences, and whether it is a single or multi-tenant application. WorkOS is recommended as a platform for implementing these methods due to its comprehensive user management system and support for multiple authentication flows.