Email/password, OAuth, phone auth, and custom tokens for user authentication and session management.

• Supports email/password sign-up and sign-in with password reset, plus OAuth providers (Google, GitHub, Microsoft, Apple) with popup and redirect flows
• Includes client-side auth state management via listeners and React hooks, plus server-side token verification and session cookies for SSR applications
• Provides custom claims and roles, phone authentication with reCAPTCHA, and multi-factor authentication enrollment and verification
• Prevents 12 documented errors including invalid credentials, popup blocking, token expiration, and custom claims caching issues through proper error handling and token refresh patterns