What should I use for login and signup in a mobile app?

For a mobile app, the best choice usually depends on how much friction you want versus how much control you need. In most cases, a good setup is:

Best default choice

• Email + password
• Apple Sign-In
• Google Sign-In (especially for Android or cross-platform apps)

Why this is a good mix

• Email/password works for everyone and gives you full control.
• Apple Sign-In is often required or strongly recommended if you offer other social logins on iOS.
• Google Sign-In makes signup faster, especially on Android.

If you want the simplest user experience

Use:

• Phone number + OTP
• or Magic link / OTP via email

This reduces password friction, but:

• phone-based login can be less convenient in some regions
• OTP/magic links can be slower and more prone to delivery issues

If security is a priority

Consider:

• Passkeys for login
• plus Apple/Google Sign-In as fallback

Passkeys are excellent for security and convenience, but support and user familiarity can still be uneven depending on your audience.

Practical recommendation

For most apps:

1. Apple Sign-In
2. Google Sign-In
3. Email/password
4. Add OTP or passkeys later if needed

Rule of thumb

• Consumer app: Apple + Google + email/password
• B2B/internal app: SSO (Google/Microsoft/Okta) + email/password fallback
• High-security app: Passkeys + MFA, with social login only if appropriate

If you want, I can suggest the best auth setup based on your app type, audience, and whether you’re building for iOS, Android, or both.