Supabase, an open-source Firebase alternative, has launched Supabase Auth, a feature that provides backend services for user authentication and authorization. Developers can now easily onboard users with functions like supabase.auth.signUp() and supabase.auth.signIn(). The system also supports Row Level Security (RLS) and policies, allowing developers to write complex SQL rules fitting their unique business needs. Supabase Auth is built using three open-source products: PostgreSQL for authorization, Netlify's GoTrue server for authentication, and PostgREST. Future updates will include custom email templates, 3rd-party OAuth providers, and a simplified policy interface.