Building a React Native App for 20+ Languages: Lessons in i18n

Building a React Native App for 20+ Languages: Lessons in i18n Supporting 20+ languages in a mobile app is not a checklist item. It's a continuous engineering commitment that touches every layer of the stack: UI layout, typography, data storage, API design, and release workflows. Here's what I learned building a language learning app with extensive multilingual support. The i18n Library Decision For React Native, the main options are: i18next + react-i18next : Most full-featured. Supports namespaces, pluralisation, interpolation, language detection. ~20KB gzipped. react-native-localize + custom solution : Lower-level, more control. Works well if your needs are simple. expo-localization : Good for Expo-managed workflow apps, limited for bare React Native. I chose i18next with react-i18next . The namespace support is critical when your translation file grows beyond 200 keys — splitting by feature (onboarding, settings, lesson, error) keeps files manageable and allows lazy loading. // i18