What is react-native-lingua?

react-native-lingua is a Duolingo-style language learning mobile app built as a tutorial project. Its main distinctive feature is a real-time AI voice teacher: instead of just tapping on answers, you can have a back-and-forth spoken conversation with an AI tutor directly in the app. The app is built with Expo and React Native, which let you write a single TypeScript codebase that runs on both iOS and Android. The voice AI feature is powered by Stream Voice Agents, a service that handles the real-time audio connection to the AI. User accounts and login, including social sign-in, are handled by Clerk, an authentication service that provides ready-made sign-in and sign-up screens. App state (tracking which lessons you're on, your progress, etc.) is managed with Zustand, a lightweight state management tool. The UI styling uses NativeWind, which lets you apply Tailwind CSS utility classes (a popular web styling approach) to mobile components. User behavior and analytics are tracked with PostHog. The project covers a full onboarding flow, lesson interface, authentication, and production monitoring. It was created as an educational resource accompanying a video tutorial from the JavaScript Mastery YouTube channel, walking through how to build the app step by step. The full README is longer than what was provided.