Topic guide · 3 min read
Social login, done properly
Short answer
Social login lets users sign in with an account they already have at a provider such as Google, Apple or Microsoft; integrate it with OpenID Connect where available, request only the scopes you need, key accounts on issuer plus subject, link accounts only on verified identifiers, and keep a non-social sign-in option.
Key takeaways
- Use the authorization code flow with PKCE and validate the ID token like any other.
- Never trust an unverified email address from a provider to link or merge accounts.
- Offer at least one sign-in method that does not depend on a single social provider.
Social login trades one problem for another. You no longer store passwords for those users, and sign-up gets faster. In return you depend on outside providers, inherit their data rules, and need to handle account linking carefully.
How does the integration work?
As a standard OpenID Connect relying party: authorization code flow with PKCE, ID token validation, then your own session.
- Register your app with the provider; get a client ID and set exact redirect URIs.
- Send users to the provider's authorization endpoint with
scope=openid email profile,state,nonceand PKCE. Build the request in the Authorization URL Builder. - Exchange the code; validate the ID token's signature,
iss,aud,expandnonce. - Look up the account by (
iss,sub); create one if new.
Providers that are not fully OpenID Connect compliant use OAuth 2.0 plus a profile API; the same principles apply.
What should I store?
The issuer and subject as the key, plus only the profile data you need.
| Field | Use | Notes |
|---|---|---|
iss + sub |
Account key | Stable per provider; never reuse across providers |
email |
Contact | May change; may be a relay address |
email_verified |
Linking decisions | Only link on true |
name |
Display | User may edit in your app |
How do I link accounts?
Only on verified identifiers, and with the user's confirmation when an existing account is involved.
Automatic merging on email has led to account takeovers: an attacker registers an unverified email at one provider and inherits the victim's account. Safer: when a new social sign-in matches an existing account's email, ask the user to sign in with the existing method first, then link.
What about privacy and consent?
Request minimal scopes, explain why, and record consent and data sources.
Users see the provider's consent screen listing what you asked for; long lists reduce sign-up. Under GDPR and similar laws, data received from a social provider is personal data you are responsible for. Honor deletion, and remember that some providers require you to handle their own account-deletion or revocation notifications.
When is a broker or CIAM platform worth it?
When you support several providers, enterprise customers' IdPs, or need consent, MFA and fraud controls at scale.
An identity broker normalizes many upstream providers into one interface for your apps; see the social corridor guide. For a broader view of CIAM, read social login and CIAM explained.
Questions
Which social providers should I offer?
The ones your users actually have. For consumer apps, Google and Apple cover most smartphone users; apps on Apple platforms that offer certain third-party logins may need Sign in with Apple under Apple's App Store rules. Business apps often add Microsoft. Check current platform policies before launch.
What data can I get from social login?
Typically a stable subject identifier, email address and whether it is verified, and name. Some providers offer more with extra scopes and review. Ask only for what you need.