How do you handle account conflicts?

If a user signed up with email and then tries to sign in with Google (same email), what happens? The most user-friendly approach is to automatically link the accounts — but this needs explicit implementation.

Is Sign in with Apple implemented for the iOS build?

If you're using any other social login on iOS, Apple requires this.

What data do you receive from each provider, and how is it stored?

Google gives you name, email, and photo. Apple gives you name and email — but only the first time. After that, Apple sends only a unique identifier.

What happens if the provider's service is down?

Users should always be able to log in with email/password as a fallback.

Does the provider's terms of service allow your use case?

Facebook's policies around what you can do with data received through their login have restrictions.

How Much Does Social Login (Google, Apple, Facebook) Cost to Add?

What is social login?

Social login lets users sign in to your app using an existing account — typically Google, Apple, or Facebook — instead of creating a new username and password. The user clicks "Sign in with Google," grants permission, and your app receives a verified identity from Google. No new password to remember, no email verification flow required.

From a user experience perspective, it reduces signup friction significantly. From a security perspective, it offloads credential management to providers that have far better security infrastructure than most apps.

Sign in with Apple deserves special mention for iOS apps: Apple's App Store guidelines require that any app offering social login from a third party (Google, Facebook) must also offer Sign in with Apple. If you're building for iOS, this isn't optional.

When does your app need it?

You want to reduce drop-off at the signup/login screen — every extra form field costs conversions
Your users are consumers rather than enterprise (B2C apps benefit more than B2B tools)
You're building a mobile app and want fast, frictionless onboarding
Your app already has Google Workspace or Microsoft 365 users who shouldn't need separate credentials
You're required to support Sign in with Apple for App Store compliance
You want to reduce password reset support volume

How much does it cost?

Adding social login typically adds 5–11 hours of development — roughly $1,000–$2,000 AUD.

The range covers implementing one to three providers. Each provider requires its own OAuth app setup, callback handling, and account-linking logic.

What adds cost:

Account linking — handling the case where a user previously signed up with email and now tries to sign in with Google using the same email address. This edge case needs explicit handling.
Profile data sync — using the user's name and profile photo from their Google/Apple/Facebook account and keeping it updated.
Enterprise/SSO providers — SAML-based SSO for enterprise customers (Okta, Azure AD) is a separate, more complex feature.

How it's typically built

Social login uses OAuth 2.0 — your app redirects the user to the provider's login page, the user authenticates there, and the provider sends back a token confirming their identity. Your app exchanges this token for user details (email, name, profile photo) and creates or finds the matching account in your database.

On the frontend, each provider has an official SDK that handles the redirect and token exchange. On the backend, the token is verified against the provider's public keys to confirm it hasn't been tampered with.

For React Native apps, expo-auth-session or react-native-app-auth handle the native OAuth flow. For web apps, libraries like NextAuth.js simplify the implementation considerably.

Questions to ask your developer

How do you handle account conflicts? If a user signed up with email and then tries to sign in with Google (same email), what happens? The most user-friendly approach is to automatically link the accounts — but this needs explicit implementation.
Is Sign in with Apple implemented for the iOS build? If you're using any other social login on iOS, Apple requires this.
What data do you receive from each provider, and how is it stored? Google gives you name, email, and photo. Apple gives you name and email — but only the first time. After that, Apple sends only a unique identifier.
What happens if the provider's service is down? Users should always be able to log in with email/password as a fallback.
Does the provider's terms of service allow your use case? Facebook's policies around what you can do with data received through their login have restrictions.

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