Firebaseui Android Getting Started

FirebaseUI Android Auth Setup

Use this skill when the user wants to add FirebaseUI Auth to an existing Android app. Assume you are working in the user's app repo, not the FirebaseUI source repo.

Default to the high-level predefined screen API: FirebaseAuthScreen with authUIConfiguration {}. Only reach for the low-level AuthFlowController (authUI.createAuthFlow(configuration), returning createIntent/authStateFlow/cancel/dispose for manual ActivityResultLauncher-based flows) or custom slot UIs when the user explicitly asks for custom auth screens.

Source References

Use these when details are needed beyond this skill:

• FirebaseUI Auth docs: https://github.com/firebase/FirebaseUI-Android/blob/master/auth/README.md
• Firebase Android setup: https://firebase.google.com/docs/android/setup
• Firebase Auth provider setup: https://firebase.google.com/docs/auth
• AuthUIStringProvider customization sample: https://github.com/firebase/FirebaseUI-Android/blob/master/auth/src/main/java/com/firebase/ui/auth/configuration/string_provider/AuthUIStringProviderSample.kt

Setup Workflow

Track this checklist while working:

• [ ] Inspect the Android project structure and identify the app module.
• [ ] Verify Firebase project configuration: google-services.json, Google Services Gradle plugin, package name, and enabled Auth providers.
• [ ] Verify Compose, Kotlin, min SDK, and FirebaseUI Auth dependencies.
• [ ] Add or adapt a predefined auth screen using FirebaseAuthScreen.
• [ ] Wire success, failure, cancel, and signed-in state handling into the app's navigation.
• [ ] Run the smallest relevant Gradle build or test task.

Firebase Project Configuration

Do not invent Firebase config values. The consumer must get them from their Firebase project.

• In the Firebase Console, add an Android app using the app's real applicationId.
• Download google-services.json and place it in the app module, usually app/google-services.json.
• Enable each provider the app will expose in Firebase Console > Authentication > Sign-in method.
• For Google Sign-In, ensure the Google Services Gradle plugin is applied and the app's package name/SHA certificates are configured in Firebase.
• For phone auth, verify the user's Firebase project supports the target regions and test numbers if needed.
• For OAuth providers such as Facebook, Twitter/X, GitHub, Microsoft, Yahoo, Apple, or custom OIDC, configure provider credentials in Firebase Console before wiring the Android UI.

Gradle Defaults

Prefer Kotlin DSL snippets when the project uses build.gradle.kts; translate to Groovy only if the project already uses Groovy.

App module essentials:

plugins {
    id("com.android.application")
    id("org.jetbrains.kotlin.android")
    id("org.jetbrains.kotlin.plugin.compose")
    id("com.google.gms.google-services")
}

android {
    buildFeatures {
        compose = true
    }
}

dependencies {
    implementation("com.firebaseui:firebase-ui-auth:10.0.0-beta03")

    implementation(platform("com.google.firebase:firebase-bom:34.7.0"))
    implementation("com.google.firebase:firebase-auth")

    implementation(platform("androidx.compose:compose-bom:2025.10.00"))
    implementation("androidx.activity:activity-compose")
    implementation("androidx.compose.ui:ui")
    implementation("androidx.compose.material3:material3")
}

Root/plugin configuration varies by project. If com.google.gms.google-services is not already available, add the Google Services plugin using the project's existing convention: plugins { ... apply false }, buildscript classpath, or version catalog.

Add provider-specific dependencies only when used. Facebook login needs:

implementation("com.facebook.android:facebook-login:18.0.3")

Minimum expectations from the FirebaseUI Auth docs: Android SDK 21+, Kotlin 1.9+, Compose compiler 1.5+, and Firebase Auth 22.0.0+. Respect stricter versions already present in the user repo.

Predefined Auth Screen Template

Adapt names, theme, navigation, and provider list to the app. Keep provider setup aligned with what is enabled in Firebase Console.

import android.os.Bundle
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.runtime.remember
import com.firebase.ui.auth.AuthException
import com.firebase.ui.auth.FirebaseAuthUI
import com.firebase.ui.auth.configuration.authUIConfiguration
import com.firebase.ui.auth.configuration.auth_provider.AuthProvider
import com.firebase.ui.auth.configuration.theme.AuthUITheme
import com.firebase.ui.auth.ui.screens.FirebaseAuthScreen

class AuthActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val authUI = FirebaseAuthUI.getInstance()

        if (authUI.isSignedIn()) {
            navigateToHome()
            finish()
            return
        }

        setContent {
            AppTheme {
                val authTheme = AuthUITheme.fromMaterialTheme()
                val configuration = remember(authTheme) {
                    authUIConfiguration {
                        context = applicationContext
                        theme = authTheme
                        providers {
                            provider(
                                AuthProvider.Email(
                                    emailLinkActionCodeSettings = null,
                                    passwordValidationRules = emptyList(),
                                )
                            )
                            provider(
                                AuthProvider.Google(
                                    scopes = emptyList(),
                                    serverClientId = null,
                                )
                            )
                        }
                    }
                }

                FirebaseAuthScreen(
                    configuration = configuration,
                    authUI = authUI,
                    onSignInSuccess = { result ->
                        navigateToHome()
                    },
                    onSignInFailure = { exception: AuthException ->
                        Toast.makeText(
                            this,
                            exception.message ?: "Authentication failed",
                            Toast.LENGTH_SHORT
                        ).show()
                    },
                    onSignInCancelled = {
                        finish()
                    }
                )
            }
        }
    }
}

If the project uses Navigation Compose, prefer making FirebaseAuthScreen a destination and call the existing NavController from callbacks instead of creating a new Activity.

Provider Notes

• Email/password works with AuthProvider.Email() and includes sign-in, sign-up, password reset, and optional display name collection.
• Google works with AuthProvider.Google() once google-services.json, Firebase provider enablement, and SHA certificates are correct.
• Anonymous sign-in uses AuthProvider.Anonymous; enable anonymous auth in Firebase Console first.
• Phone uses AuthProvider.Phone(...); configure country defaults only when the product has a clear country policy.
• Facebook uses AuthProvider.Facebook() plus the Facebook SDK dependency and these string resources:

<string name="facebook_application_id" translatable="false">YOUR_FACEBOOK_APP_ID</string>
<string name="facebook_login_protocol_scheme" translatable="false">fbYOUR_FACEBOOK_APP_ID</string>
<string name="facebook_client_token" translatable="false">CHANGE-ME</string>

• Generic OIDC and SAML providers use AuthProvider.GenericOAuth(...) with the provider ID exactly as configured in Firebase Console, for example oidc.line or saml.mycompany.

String Customization

Only add this when the user explicitly asks to change wording or branding, not by default.

Set stringProvider on authUIConfiguration { } to override built-in UI copy. Delegate to DefaultAuthUIStringProvider(context) via Kotlin interface delegation and override only the strings that need to change:

class CustomAuthUIStringProvider(
    private val defaultProvider: AuthUIStringProvider
) : AuthUIStringProvider by defaultProvider {
    override val signInWithGoogle: String = "Continue with Google"
    override val continueText: String = "Continue to MyApp"
}

val configuration = authUIConfiguration {
    context = applicationContext
    providers { /* ... */ }
    stringProvider = CustomAuthUIStringProvider(DefaultAuthUIStringProvider(applicationContext))
}

Theming

Only customize shapes/colors when the user asks for brand-specific styling; the defaults are fine otherwise. Set theme on authUIConfiguration { } using AuthUITheme:

// Adjust provider button corner radius globally
val theme = AuthUITheme.Default.copy(providerButtonShape = RoundedCornerShape(12.dp))

// Inherit from the app's Material theme instead of FirebaseUI defaults
val theme = AuthUITheme.fromMaterialTheme(providerButtonShape = RoundedCornerShape(12.dp))

// Override shape/color for individual providers
val theme = AuthUITheme.Default.copy(
    providerButtonShape = RoundedCornerShape(12.dp),
    providerStyles = mapOf(
        "google.com" to ProviderStyleDefaults.Google.copy(shape = RoundedCornerShape(24.dp)),
        "facebook.com" to ProviderStyleDefaults.Facebook.copy(shape = RoundedCornerShape(8.dp)),
    )
)

Content Slots

Only wire these when the user explicitly asks for custom auth screens; default to the predefined FirebaseAuthScreen UI otherwise. FirebaseAuthScreen accepts optional composable slot parameters that replace individual screens while keeping navigation, error handling, and MFA flow intact:

• emailContent: (@Composable (EmailAuthContentState) -> Unit)? — replaces the email sign-in/sign-up/reset UI.
• phoneContent: (@Composable (PhoneAuthContentState) -> Unit)? — replaces the phone auth UI.
• customMethodPickerLayout: (@Composable (List<AuthProvider>, (AuthProvider) -> Unit) -> Unit)? — replaces the provider list on the method picker screen.
• customMethodPickerTermsConfiguration: MethodPickerTermsConfiguration? — replaces the default "By continuing..." terms footer with custom content, for example a consent checkbox. Takes content, accepted, and optionally disableProvidersUntilAccepted = true to gate sign-in until consent is given.
• mfaEnrollmentContent, mfaChallengeContent, reauthContent, authenticatedContent — replace MFA enrollment, MFA challenge, reauthentication, and the post-sign-in state respectively.

Each slot receives a state object with the same fields/callbacks the default UI uses (e.g. EmailAuthContentState exposes email, password, isLoading, onEmailChange, onSignInClick, etc.). Read the corresponding state class before writing custom UI so field names are correct.

reauthContent only appears when triggered. Wrap sensitive operations (updating a password, deleting the account, etc.) in authUI.withReauth(context, reason = "...") { /* operation */ }; if the wrapped call throws AuthException.InvalidCredentialsException, FirebaseAuthScreen automatically navigates to reauthContent (or its default bottom sheet if no custom slot is provided) to re-verify the user before retrying.

Gotchas

• Never commit a real google-services.json unless the user's repo already treats Firebase config as committable and they explicitly want it included.
• Do not hard-code demo package names, server client IDs, OAuth IDs, policy URLs, or Firebase project values from FirebaseUI samples.
• FirebaseUI Auth releases may be built with newer Kotlin metadata than the app. If compilation reports incompatible Kotlin metadata, update the app's Kotlin plugin or choose a FirebaseUI version compatible with the app's Kotlin version.
• If provider constructors fail because optional parameters have no defaults, pass explicit values such as AuthProvider.Email(emailLinkActionCodeSettings = null, passwordValidationRules = emptyList()) and AuthProvider.Google(scopes = emptyList(), serverClientId = null).
• Remember the authUIConfiguration object in Compose so recomposition does not recreate or restart the auth flow.
• Google Sign-In failures are often Firebase Console or SHA certificate issues, not Kotlin code issues.
• Keep the provider list small at first. Add only providers the user has configured and can test.
• Set theme in authUIConfiguration for clarity. Use an AuthUITheme wrapper only if surrounding UI must share that theme.
• For email-link sign-in, configure actionCodeSettings, handle the incoming deep link, and add the matching manifest intent filter. Do not add email-link support unless requested.

Validation

After edits, run the smallest command that proves the integration compiles, such as:

./gradlew :app:assembleDebug

If the build fails, first check dependency versions, Compose enablement, the Google Services plugin, and whether google-services.json is in the app module. Report any Firebase Console steps the agent cannot complete locally.