Firebase Authentication provides backend services, easy-to-use SDKs, and ready-made UI libraries to authenticate users to your app.
Users
A user is an entity that can sign in to your app. Each user is identified by a unique ID (
uid
) which is guaranteed to be unique across all providers.
User properties include:
uid
Unique identifier.
email
User's email address (if available).
displayName
User's display name (if available).
photoURL
URL to user's photo (if available).
emailVerified
Boolean indicating if the email is verified.
Identity Providers
Firebase Auth supports multiple ways to sign in:
Email/Password
Basic email and password authentication.
Federated Identity Providers
Google, Facebook, Twitter, GitHub, Microsoft, Apple, etc.
Phone Number
SMS-based authentication.
Anonymous
Temporary guest accounts that can be linked to permanent accounts later.
Custom Auth
Integrate with your existing auth system.
Google Sign In is recommended as a good and secure default provider.
Tokens
When a user signs in, they receive an ID Token (JWT). This token is used to identify the user when making requests to Firebase services (Realtime Database, Cloud Storage, Firestore) or your own backend.
ID Token
Short-lived (1 hour), verifies identity.
Refresh Token
Long-lived, used to get new ID tokens.
Workflow
1. Provisioning
Option 1. Enabling Authentication via CLI
Only Google Sign In, anonymous auth, and email/password auth can be enabled via CLI. For other providers, use the Firebase Console.
Configure Firebase Authentication in
firebase.json
by adding an 'auth' block:
{
"auth": {
"providers": {
"anonymous": true,
"emailPassword": true,
"googleSignIn": {
"oAuthBrandDisplayName": "Your Brand Name",
"supportEmail": "support@example.com",
"authorizedRedirectUris": ["https://example.com"]
}
}
}
}
Option 2. Enabling Authentication in Console
Enable other providers in the Firebase Console.
Go to the
https://console.firebase.google.com/project/_/authentication/providers
Select your project.
Enable the desired Sign-in providers (e.g., Email/Password, Google).
2. Client Setup & Usage
Web
See
references/client_sdk_web.md
.
3. Security Rules
Secure your data using
request.auth
in Firestore/Storage rules.
See
references/security_rules.md
.