You can use Firebase Authentication to create and use temporary anonymous accounts
to authenticate with Firebase. These temporary anonymous accounts can be used to
allow users who haven't yet signed up to your app to work with data protected
by security rules. If an anonymous user decides to sign up to your app, you can
link their sign-in credentials to the anonymous
account
so that they can continue to work with their protected data in
future sessions.
Before you begin
- Add Firebase to your JavaScript project
.
- If you haven't yet connected your app to your Firebase project, do so from
the
Firebase console
.
- Enable anonymous auth:
- In the
Firebase console
, open the
Auth
section.
- On the
Sign-in Methods
page, enable the
Anonymous
sign-in method.
- Optional
: If you've upgraded your project to
Firebase Authentication with Identity Platform
, you can enable automatic clean-up. When
you enable this setting, anonymous accounts older than 30 days will be automatically
deleted. In projects with automatic clean-up enabled, anonymous authentication will no
longer count toward usage limits or billing quotas. See
Automatic clean-up
.
Authenticate with Firebase anonymously
When a signed-out user uses an app feature that requires authentication with
Firebase, sign in the user anonymously by completing the following steps:
- Call the
signInAnonymously
method:
Web modular API
import { getAuth, signInAnonymously } from "firebase/auth";
const auth = getAuth();
signInAnonymously(auth)
.then(() => {
// Signed in..
})
.catch((error) => {
const errorCode = error.code;
const errorMessage = error.message;
// ...
});
Web namespaced API
firebase.auth().signInAnonymously()
.then(() => {
// Signed in..
})
.catch((error) => {
var errorCode = error.code;
var errorMessage = error.message;
// ...
});
This is also where you can catch and handle errors. For a list of error codes have a look at the
Auth Reference Docs
.
- If the
signInAnonymously
method completes without error, the observer registered in the
onAuthStateChanged
will trigger and you can get the anonymous user's account data from the
User
object:
Web modular API
import { getAuth, onAuthStateChanged } from "firebase/auth";
const auth = getAuth();
onAuthStateChanged(auth, (user) => {
if (user) {
// User is signed in, see docs for a list of available properties
// https://firebase.google.com/docs/reference/js/auth.user
const uid = user.uid;
// ...
} else {
// User is signed out
// ...
}
});
Web namespaced API
firebase.auth().onAuthStateChanged((user) => {
if (user) {
// User is signed in, see docs for a list of available properties
// https://firebase.google.com/docs/reference/js/v8/firebase.User
var uid = user.uid;
// ...
} else {
// User is signed out
// ...
}
});
Convert an anonymous account to a permanent account
When an anonymous user signs up to your app, you might want to allow them to
continue their work with their new account—for example, you might want to
make the items the user added to their shopping cart before they signed up
available in their new account's shopping cart. To do so, complete the following
steps:
- When the user signs up, complete the sign-in flow for the user's
authentication provider up to, but not including, calling one of the
Auth.signInWith
methods. For example, get the user's Google ID token,
Facebook access token, or email address and password.
Get an
AuthCredential
for the new authentication provider:
Google Sign-In
Web modular API
import { GoogleAuthProvider } from "firebase/auth";
const credential = GoogleAuthProvider.credential(
googleUser.getAuthResponse().id_token);
Web namespaced API
var credential = firebase.auth.GoogleAuthProvider.credential(
googleUser.getAuthResponse().id_token);
Facebook Login
Web modular API
import { FacebookAuthProvider } from "firebase/auth";
const credential = FacebookAuthProvider.credential(
response.authResponse.accessToken);
Web namespaced API
var credential = firebase.auth.FacebookAuthProvider.credential(
response.authResponse.accessToken);
Email-password sign-in
Web modular API
import { EmailAuthProvider } from "firebase/auth";
const credential = EmailAuthProvider.credential(email, password);
Web namespaced API
var credential = firebase.auth.EmailAuthProvider.credential(email, password);
Pass the
AuthCredential
object to the sign-in user's
link
method:
Web modular API
import { getAuth, linkWithCredential } from "firebase/auth";
const auth = getAuth();
linkWithCredential(auth.currentUser, credential)
.then((usercred) => {
const user = usercred.user;
console.log("Anonymous account successfully upgraded", user);
}).catch((error) => {
console.log("Error upgrading anonymous account", error);
});
Web namespaced API
auth.currentUser.linkWithCredential(credential)
.then((usercred) => {
var user = usercred.user;
console.log("Anonymous account successfully upgraded", user);
}).catch((error) => {
console.log("Error upgrading anonymous account", error);
});
If the call to
link
succeeds, the user's new account can
access the anonymous account's Firebase data.
Automatic clean-up
If you've upgraded your project to
Firebase Authentication with Identity Platform
, you can
enable automatic clean-up in the Firebase console. When you enable this feature you allow
Firebase to automatically delete anonymous accounts older than 30 days. In projects with automatic
clean-up enabled, anonymous authentication will not count toward usage limits or billing quotas.
- Any anonymous accounts created after enabling automatic clean-up might be automatically
deleted any time after 30 days post-creation.
- Existing anonymous accounts will be eligible for automatic deletion 30 days after
enabling automatic clean-up.
- If you turn automatic clean-up off, any anonymous accounts scheduled to be deleted will remain
scheduled to be deleted.
- If you "upgrade" an anonymous account by linking it to any sign-in method, the account will
not get automatically deleted.
If you want to see how many users will be affected before you enable this feature, and you've
upgraded your project to
Firebase Authentication with Identity Platform
, you can filter by
is_anon
in
Cloud
Logging
.
Next steps
Now that users can authenticate with Firebase, you can control their access to
data in your Firebase database using
Firebase rules
.