Adopting Cross-Platform React Native at Scale: Zalando’s Learnings

Zalando had separate iOS and Android codebases totaling about 500,000 lines, built over 10 years. The team wanted faster development and experimentation while keeping the existing app running and preparing for future needs, including web.

Eichhorn describes integrating React Native screen by screen, with A/B tests to control rollout. Zalando aimed to avoid disrupting native engineers’ workflows or carrying existing architecture’s technical debt into the new setup.

The React Native entry point is packaged for two consumers: a standalone development app and a framework used by the production app. A prebuilt developer app connects to local Metro or CI bundles, while the production framework exposes a small API for initialization and creating native views.

Zalando aimed to share useful code across web and mobile while preserving platform differences. Its existing Rendering Engine provides common application concepts such as data fetching and caching; React Strict maps HTML-like elements to platform components, and shared component libraries can use platform-specific files when needed.

Zalando’s Traits library defines typed actions and state so modules can depend on capabilities such as navigation without depending on their implementation. Teams can share logic or use different implementations by platform, preserving the option to build native features.