This page shows you how to enable App Check in a Flutter app, using the
default providers: Play Integrity on Android, Device Check on Apple platforms, and
reCAPTCHA v3 on web. When you enable App Check, you help ensure that
only your app can access your project's Firebase resources. See an
[Overview](https://firebase.google.com/docs/app-check.md.txt) of this feature.

## 1. Set up your Firebase project

1. [Install and initialize FlutterFire](https://firebase.google.com/docs/flutter/setup.md.txt) if you haven't
   already done so.

2. In the Firebase console, navigate to **Security** \>
   [**App Check**](https://console.firebase.google.com/project/_/appcheck/).

3. In the **Apps** tab, register your apps to use App Check with the
   Play Integrity, DeviceCheck, and reCAPTCHA providers.

   You usually need to register all of your project's apps, because once you
   enable enforcement for a Firebase product, only registered apps will be able
   to access the product's backend resources.
4. **Optional**: In the app registration settings, set a custom time-to-live
   (TTL) for App Check tokens issued by the provider. You can set the TTL
   to any value between 30 minutes and 7 days. When changing this value, be
   aware of the following tradeoffs:

   - Security: Shorter TTLs provide stronger security, because it reduces the window in which a leaked or intercepted token can be abused by an attacker.
   - Performance: Shorter TTLs mean your app will perform attestation more frequently. Because the app attestation process adds latency to network requests every time it's performed, a short TTL can impact the performance of your app.
   - Quota and cost: Shorter TTLs and frequent re-attestation deplete your quota faster, and for paid services, potentially cost more. See [Quotas \& limits](https://firebase.google.com/docs/app-check.md.txt#quotas_limits).

   The default TTL
   is reasonable for most apps. Note that the App Check library refreshes
   tokens at approximately half the TTL duration.

## 2. Add the App Check library to your app

1. From the root of your Flutter project, run the following command to install the plugin:

   ```bash
   flutter pub add firebase_app_check
   ```
2. Once complete, rebuild your Flutter application:

   ```bash
   flutter run
   ```

## 3. Initialize App Check

Add the following initialization code to your app so that it runs before you
use any Firebase services such as Storage, but after calling
`Firebase.initializeApp()`;

```dart
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';

// Import the firebase_app_check plugin
import 'package:firebase_app_check/firebase_app_check.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  await FirebaseAppCheck.instance.activate(
    // You can also use a `ReCaptchaEnterpriseProvider` provider instance as an
    // argument for `webProvider`
    webProvider: ReCaptchaV3Provider('recaptcha-v3-site-key'),
    // Default provider for Android is the Play Integrity provider. You can use the "AndroidProvider" enum to choose
    // your preferred provider. Choose from:
    // 1. Debug provider
    // 2. Safety Net provider
    // 3. Play Integrity provider
    androidProvider: AndroidProvider.debug,
    // Default provider for iOS/macOS is the Device Check provider. You can use the "AppleProvider" enum to choose
        // your preferred provider. Choose from:
        // 1. Debug provider
        // 2. Device Check provider
        // 3. App Attest provider
        // 4. App Attest provider with fallback to Device Check provider (App Attest provider is only available on iOS 14.0+, macOS 14.0+)
    appleProvider: AppleProvider.appAttest,
  );
  runApp(App());
}
```

## Next steps

Once the App Check library is installed in your app, start distributing the
updated app to your users.

The updated client app will begin sending App Check tokens along with every
request it makes to Firebase, but Firebase products will not require the tokens
to be valid until you enable enforcement in the App Check section of the
Firebase console.

### Monitor metrics and enable enforcement

Before you enable enforcement, however, you should make sure that doing so won't
disrupt your existing legitimate users. On the other hand, if you're seeing
suspicious use of your app resources, you might want to enable enforcement
sooner.

To help make this decision, you can look at App Check metrics for the
services you use:

- [Monitor App Check request metrics](https://firebase.google.com/docs/app-check/monitor-metrics.md.txt) for Realtime Database, Cloud Firestore, Cloud Storage, and Authentication.
- [Monitor App Check request metrics for Cloud Functions](https://firebase.google.com/docs/app-check/monitor-functions-metrics.md.txt).

### Enable App Check enforcement

When you understand how App Check will affect your users and you're ready to
proceed, you can enable App Check enforcement:

- [Enable App Check enforcement](https://firebase.google.com/docs/app-check/enable-enforcement.md.txt) for Realtime Database, Cloud Firestore, Cloud Storage, and Authentication.
- [Enable App Check enforcement for Cloud Functions](https://firebase.google.com/docs/app-check/cloud-functions.md.txt).

### Use App Check in debug environments

If, after you have registered your app for App Check, you want to run your
app in an environment that App Check would normally not classify as valid,
such as an emulator during development, or from a continuous integration (CI)
environment, you can create a debug build of your app that uses the
App Check debug provider instead of a real attestation provider.

See [Use App Check with the debug provider in Flutter apps](https://firebase.google.com/docs/app-check/flutter/debug-provider.md.txt).

> [!NOTE]
> **Note:** For certain Android devices, you need to enable "Meets basic device integrity" in the Google Play console.