Acknowledgements

We use these open source libraries to make Duolingo:

ANR-Watchdog
Activity Kotlin Extensions
Adapter: RxJava 3
Adjust Android SDK
Android AppCompat Library
Android ConstraintLayout
Android Lifecycle Process
Android Lifecycle Service
Android Lifecycle ViewModel Kotlin Extensions
Android Lifecycle ViewModel with SavedState
Android Lifecycle WorkManager Hilt Extension
Android Room RXJava3
Android Room-Runtime
Android WorkManager Kotlin Extensions
Android WorkManager RxJava3 Support
AndroidSVG
AndroidX Autofill
AndroidX Widget ViewPager2
Audience-Network-SDK
Core Kotlin Extensions
Facebook mediation adapter for the Google Mobile Ads SDK
Facebook-Android-SDK
FlowLayouts
Fragment Kotlin Extensions
GoogleConversionTrackingSdk
Gson
HanziVG
Hilt Android
KanjiVG
LeakCanary Object Watcher for Android - Core
Lottie
Material Components for Android
Network Connection Class
PCollections
Picasso
Retrofit
RxAndroid
RxJava
RxJava Replaying Share (Kotlin Extensions)
RxKotlin
ShortcutBadger
SplashScreen
Support Annotations
Support CardView v7
Support Custom Tabs
Support DynamicAnimation
Support Grid Layout
Support RecyclerView
Support v4
Ticker
UnityAds mediation adapter for the Google Mobile Ads SDK
Use Plumber Android to fix known leaks in the Android Framework and other Google Android libraries.
Volley
Zendesk Support SDK
adjust-android-signaturev2
androidx.core:core
androidx.vectordrawable:vectordrawable
billing
com.android.installreferrer:installreferrer
com.duolingo.rlottie:axrlottie
com.facebook.battery:metrics-jetified
com.fullstory:instrumentation-full
com.github.PhilJay:MPAndroidChart
com.google.android.play:core-ktx
com.google.android:flexbox
com.googlecode.libphonenumber:libphonenumber
com.jraska:falcon
com.tencent.mm.opensdk:wechat-sdk-android-without-mta
commons-io
core
firebase-analytics
firebase-crashlytics
firebase-crashlytics-ndk
firebase-messaging
icu4j
okhttp
okhttp-urlconnection
play-services-ads
play-services-auth
play-services-auth-api-phone
play-services-plus
recaptcha
rive-android
unity-ads