You can use Firebase Authentication to let your users authenticate with Firebase using their email addresses and passwords, and to manage your app's password-based accounts. ### AI prompt for AI assistance ***For AI assistance, copy the prompt below into your AI coding agent (like Gemini in Android Studio, Antigravity, Claude Code, Codex, and Cursor).** You can customize the prompt and iterate with your agent. Visit [Firebase agent skills](https://firebase.google.com/docs/ai-assistance/agent-skills.md.txt) for detailed installation info.* ``` Help me use Firebase in my app. 1. Make sure that **Firebase agent skills** are installed and updated. For Claude Code, Codex, or Cursor agents, help me install the Firebase plugin. For other agents, run `npx skills add firebase/agent-skills`. Always try to use **Firebase agent skills** for Firebase-related tasks. 2. Help me set up and use Firebase Authentication with email and password authentication in my app. ``` ## Before you begin 1. If you haven't already, [add Firebase to your Android project](https://firebase.google.com/docs/android/setup.md.txt). 2. If you haven't yet connected your app to your Firebase project, do so from the [Firebase console](https://console.firebase.google.com/). 3. Enable Email/Password as a sign-in provider for your Firebase project: 1. In the Firebase console, go to **Security** \> [**Authentication**](https://console.firebase.google.com/project/_/authentication/). 2. In the **Sign-in method** tab, enable the **Email/password** sign-in provider. 3. Click **Save**. > [!NOTE] > **Tip:** If you prefer to use the [Firebase CLI](https://firebase.google.com/docs/cli.md.txt), run `firebase init auth` to configure authentication providers, and then run `firebase deploy --only auth` to deploy the changes to your project. 4. In your **module (app-level) Gradle file** (usually `//build.gradle.kts` or `//build.gradle`), add the dependency for the Firebase Authentication library for Android. We recommend using the [Firebase Android BoM](https://firebase.google.com/docs/android/learn-more.md.txt#bom) to control library versioning. ``` dependencies { // Import the BoM for the Firebase platform implementation(platform("com.google.firebase:firebase-bom:35.1.0")) // Add the dependency for the Firebase Authentication library // When using the BoM, you don't specify versions in Firebase library dependencies implementation("com.google.firebase:firebase-auth") } ``` By using the [Firebase Android BoM](https://firebase.google.com/docs/android/learn-more.md.txt#bom), your app will always use compatible versions of Firebase Android libraries. *(Alternative)* Add Firebase library dependencies *without* using the BoM If you choose not to use the Firebase BoM, you must specify each Firebase library version in its dependency line. **Note that if you use *multiple* Firebase libraries in your app, we strongly recommend using the BoM to manage library versions, which ensures that all versions are compatible.** ```groovy dependencies { // Add the dependency for the Firebase Authentication library // When NOT using the BoM, you must specify versions in Firebase library dependencies implementation("com.google.firebase:firebase-auth:25.0.0") } ```
## Create a password-based account To create a new user account with a password, complete the following steps in your app's sign-in activity: 1. In your sign-up activity's `onCreate` method, get the shared instance of the `FirebaseAuth` object: ### Kotlin ```kotlin private lateinit var auth: FirebaseAuth // ... // Initialize Firebase Auth auth = Firebase.auth ``` ### Java ```java private FirebaseAuth mAuth; // ... // Initialize Firebase Auth mAuth = FirebaseAuth.getInstance(); ``` 2. When initializing your Activity, check to see if the user is currently signed in: ### Kotlin ```kotlin public override fun onStart() { super.onStart() // Check if user is signed in (non-null) and update UI accordingly. val currentUser = auth.currentUser if (currentUser != null) { reload() } } ``` ### Java ```java @Override public void onStart() { super.onStart(); // Check if user is signed in (non-null) and update UI accordingly. FirebaseUser currentUser = mAuth.getCurrentUser(); if(currentUser != null){ reload(); } } ``` 3. When a new user signs up using your app's sign-up form, complete any new account validation steps that your app requires, such as verifying that the new account's password was correctly typed and meets your complexity requirements. 4. Create a new account by passing the new user's email address and password to `createUserWithEmailAndPassword`: ### Kotlin ```kotlin auth.createUserWithEmailAndPassword(email, password) .addOnCompleteListener(this) { task -> if (task.isSuccessful) { // Sign in success, update UI with the signed-in user's information Log.d(TAG, "createUserWithEmail:success") val user = auth.currentUser updateUI(user) } else { // If sign in fails, display a message to the user. Log.w(TAG, "createUserWithEmail:failure", task.exception) Toast.makeText( baseContext, "Authentication failed.", Toast.LENGTH_SHORT, ).show() updateUI(null) } } ``` ### Java ```java mAuth.createUserWithEmailAndPassword(email, password) .addOnCompleteListener(this, new OnCompleteListener() { @Override public void onComplete(@NonNull Task task) { if (task.isSuccessful()) { // Sign in success, update UI with the signed-in user's information Log.d(TAG, "createUserWithEmail:success"); FirebaseUser user = mAuth.getCurrentUser(); updateUI(user); } else { // If sign in fails, display a message to the user. Log.w(TAG, "createUserWithEmail:failure", task.getException()); Toast.makeText(EmailPasswordActivity.this, "Authentication failed.", Toast.LENGTH_SHORT).show(); updateUI(null); } } }); ``` If the new account was created, the user is also signed in. In the callback, you can use the `getCurrentUser` method to get the user's account data. To protect your project from abuse, Firebase limits the number of new email/password and anonymous sign-ups that your application can have from the same IP address in a short period of time. You can request and schedule temporary changes to this quota from the Firebase console (go to the **Security** \> **Authentication** \> [**Sign-in method** tab](https://console.firebase.google.com/project/_/authentication/providers)). ## Sign in a user with an email address and password The steps for signing in a user with a password are similar to the steps for creating a new account. In your app's sign-in activity, do the following: 1. In your sign-in activity's `onCreate` method, get the shared instance of the `FirebaseAuth` object: ### Kotlin ```kotlin private lateinit var auth: FirebaseAuth // ... // Initialize Firebase Auth auth = Firebase.auth ``` ### Java ```java private FirebaseAuth mAuth; // ... // Initialize Firebase Auth mAuth = FirebaseAuth.getInstance(); ``` 2. When initializing your Activity, check to see if the user is currently signed in: ### Kotlin ```kotlin public override fun onStart() { super.onStart() // Check if user is signed in (non-null) and update UI accordingly. val currentUser = auth.currentUser if (currentUser != null) { reload() } } ``` ### Java ```java @Override public void onStart() { super.onStart(); // Check if user is signed in (non-null) and update UI accordingly. FirebaseUser currentUser = mAuth.getCurrentUser(); if(currentUser != null){ reload(); } } ``` 3. When a user signs in to your app, pass the user's email address and password to `signInWithEmailAndPassword`: ### Kotlin ```kotlin auth.signInWithEmailAndPassword(email, password) .addOnCompleteListener(this) { task -> if (task.isSuccessful) { // Sign in success, update UI with the signed-in user's information Log.d(TAG, "signInWithEmail:success") val user = auth.currentUser updateUI(user) } else { // If sign in fails, display a message to the user. Log.w(TAG, "signInWithEmail:failure", task.exception) Toast.makeText( baseContext, "Authentication failed.", Toast.LENGTH_SHORT, ).show() updateUI(null) } } ``` ### Java ```java mAuth.signInWithEmailAndPassword(email, password) .addOnCompleteListener(this, new OnCompleteListener() { @Override public void onComplete(@NonNull Task task) { if (task.isSuccessful()) { // Sign in success, update UI with the signed-in user's information Log.d(TAG, "signInWithEmail:success"); FirebaseUser user = mAuth.getCurrentUser(); updateUI(user); } else { // If sign in fails, display a message to the user. Log.w(TAG, "signInWithEmail:failure", task.getException()); Toast.makeText(EmailPasswordActivity.this, "Authentication failed.", Toast.LENGTH_SHORT).show(); updateUI(null); } } }); ``` If sign-in succeeded, you can use the returned `FirebaseUser` to proceed. ## Recommended: Set a password policy [Video](https://www.youtube.com/watch?v=smB-4UogJpQ) You can improve account security by enforcing password complexity requirements. To configure a password policy for your project, open the **Password policy** section in the **Security** \> **Authentication** \> **Settings** tab of the Firebase console: [Authentication Settings](https://console.firebase.google.com/project/_/authentication/settings) Firebase Authentication password policies support the following password requirements: - Lowercase character required - Uppercase character required - Numeric character required - Non-alphanumeric character required The following characters satisfy the non-alphanumeric character requirement: `^ $ * . [ ] { } ( ) ? " ! @ # % & / \ , > < ' : ; | _ ~` - Minimum password length (ranges from 6 to 30 characters; defaults to 6) - Maximum password length (maximum length of 4096 characters) You can enable password policy enforcement in two modes: - **Require**: Attempts to sign up fail until the user updates to a password that complies with your policy. - **Notify**: Users are allowed to sign up with a non-compliant password. When using this mode, you should check if the user's password complies with the policy on the client side and prompt the user in some way to update their password if it does not comply. New users are always required to choose a password that complies with your policy. If you have active users, we recommend not enabling force upgrade on sign in unless you intend to block access to users whose passwords don't comply with your policy. Instead, use notify mode, which allows users to sign in with their current passwords, and inform them of the requirements their password lacks. ## Recommended: Enable email enumeration protection > [!NOTE] > **Note:** If you created your project on or after September 15, 2023, email enumeration protection is enabled by default. Some Firebase Authentication methods that take email addresses as parameters throw specific errors if the email address is unregistered when it must be registered (for example, when signing in with an email address and password), or registered when it must be unused (for example, when changing a user's email address). While this can be helpful for suggesting specific remedies to users, it can also be abused by malicious actors to discover the email addresses registered by your users. To mitigate this risk, we recommend that you make sure [email enumeration protection](https://cloud.google.com/identity-platform/docs/admin/email-enumeration-protection) is enabled for your project. You can check this setting in the Firebase console: go to the **Security** \> **Authentication** \> [**Settings** tab](https://console.firebase.google.com/project/_/authentication/settings?useAutoProject=true), and then click **User actions**. Note that enabling this feature changes the error reporting behavior for Firebase Authentication, so make sure your app doesn't rely on the more specific errors. ## Next steps After a user signs in for the first time, a new user account is created and linked to the credentials---that is, the user name and password, phone number, or auth provider information---the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in. - In your apps, you can get the user's basic profile information from the [`FirebaseUser`](https://firebase.google.com/docs/reference/android/com/google/firebase/auth/FirebaseUser.md.txt) object. See [Manage Users](https://firebase.google.com/docs/auth/android/manage-users.md.txt). - In your Firebase Realtime Database and Cloud Storage [Security Rules](https://firebase.google.com/docs/database/security/user-security), you can get the signed-in user's unique user ID from the `auth` variable, and use it to control what data a user can access. You can allow users to sign in to your app using multiple authentication providers by [linking auth provider credentials to an existing user account.](https://firebase.google.com/docs/auth/android/account-linking) To sign out a user, call [`signOut`](https://firebase.google.com/docs/reference/android/com/google/firebase/auth/FirebaseAuth.md.txt#signOut()): ### Kotlin ```kotlin Firebase.auth.signOut() ``` ### Java ```java FirebaseAuth.getInstance().signOut(); ```