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SingleSign vs Firebase Authentication

In short

SingleSign vs Firebase Authentication comes down to portability: Firebase ties sign-in to the Google Cloud project it lives in, SingleSign is a standalone OpenID Connect provider.
SingleSign compared with Firebase Authentication
 SingleSignFirebase Authentication
Coupled to a cloud projectFirebase Authentication belongs to a Firebase / Google Cloud project.NoYes
Standard OpenID Connect providerFirebase issues its own ID tokens and expects its SDKs; it is not a general-purpose OIDC provider for third-party apps.YesPartly
Users are exportableFirebase exports users including password hashes, so a migration is real work but not a dead end.Not applicableYes
Client SDK requiredNoRecommended
Works with any OIDC client libraryYesNo
You store user recordsNoYes
Deep integration with other cloud servicesFirestore security rules, Cloud Functions triggers and Analytics all read Firebase Auth directly.NoYes
Free at low volumeYesYes
Per-application consent visible to the userYesNo

SingleSign is an identity provider: the account belongs to the person and they bring it to your application, the way "Sign in with Google" works. Auth0, Okta and Firebase Authentication are customer identity platforms: your application owns its own user directory and you run sign-up, storage and recovery inside it. Neither model is better in the abstract — but they are different products, and most comparisons skip past that.

Choose SingleSign when

  • Sign-in needs to outlive the cloud project it started in.
  • You want any standard OIDC client library to work, on any platform.
  • You are decoupling from Google Cloud and do not want identity to be the thing that blocks it.

Choose Firebase Authentication when

  • The rest of your stack is Firebase and your security rules depend on its auth state.
  • You want anonymous accounts that upgrade to permanent ones later.
  • You need phone-number sign-in with SMS handled for you.
  • Tight coupling to Firestore and Cloud Functions is a feature for you, not a risk.

Cost

Firebase Authentication is free for standard sign-in at typical volumes, with advanced features billed through Google Cloud Identity Platform. SingleSign sign-in is free.

Pricing checked 2026-09-21. Providers change plans — verify before you commit: Firebase pricing, SingleSign pricing.

Free to try, and there is no user directory to set up.

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