Scaling React Native at Zalando: How Brownfield Migration Paid Off
Scaling React Native at Zalando: How Brownfield Migration Paid Off
Discover how Zalando scaled React Native across a massive e-commerce app, from internal buy-in to brownfield rollout, and what they learned.
Scaling React Native at Zalando: How Brownfield Migration Paid Off

Watch the full webinar replay to see how Zalando’s engineers structured their brownfield migration and what lessons they shared for teams adopting React Native at scale. Here’s a recap if you’re more of a reader:
Why React Native and why now
Zalando’s mobile teams faced the limits of decade-old native architectures. Their business needed faster iteration, shared logic, and a unified platform experience. With an established internal framework, the Rendering Engine, built on React for web, React Native emerged as the natural fit. It allowed them to reuse existing knowledge, code, and developer skill sets across iOS, Android, and web.
Building consensus in a native world
Migrating an app at Zalando’s scale meant more than a technical shift. It required alignment across hundreds of engineers and multiple teams. The group approached this through extensive research, open communication, and a strong proof of concept. A POC built in 15 days demonstrated tangible results, showing React Native could integrate with Zalando’s Rendering Engine and run live in production without disruption.
The brownfield strategy
Zalando chose a brownfield approach: integrating React Native gradually into the existing app rather than rewriting it. Screens were rolled out one by one behind feature flags and A/B tests, starting with low-traffic areas to validate stability before expanding to complex, high-traffic screens. This de-risked the migration while maintaining business continuity.
A modular architecture for scale
The team built React Native as a self-contained SDK using dependency injection to communicate with native layers. This allowed React Native screens to live independently without inheriting legacy technical debt. On top of this, a cross-platform component library, powered by StyleX and React Strict DOM, enabled shared UI between mobile and web.
Results and next steps
The strategy proved itself: as of November 2025, four screens are fully live, twelve in testing, and seven more code-complete. Native teams have successfully shipped React Native screens (some as complex as the home screen) within weeks. By early 2026, Zalando expects 90% of app traffic to run on React Native.
Next on the roadmap: deeper observability, list performance optimizations, debt cleanup, and continued open-source collaboration.
Scaling React Native at Zalando: How Brownfield Migration Paid Off
Discover how Zalando scaled React Native across a massive e-commerce app, from internal buy-in to brownfield rollout, and what they learned.

Learn more about Brownfield
Here's everything we published recently on this topic.
We can help you move
it forward!
At Callstack, we work with companies big and small, pushing React Native everyday.
Code Sharing
Implement effective code-sharing strategies across all platforms to accelerate shipping and reduce code duplication.
Migration to React Native
Plan and execute a migration from native or hybrid stacks to React Native with minimal disruption and clear technical direction.
React Native Brownfield
Integrate React Native into existing native application and start sharing code across platforms immediately.
React Native Trainings
Equip your team with React Native skills through tailored training sessions.

React Native Performance Optimization
Improve React Native apps speed and efficiency through targeted performance enhancements.
Quality Assurance
Combine automated and manual testing with CI/CD integration to catch issues early and deliver reliable React Native releases.
Scalability Engineering
Design and validate React Native architectures that scale-supporting high traffic, modular teams, and long-term performance.
Code Sharing
Implement effective code-sharing strategies across all platforms to accelerate shipping and reduce code duplication.


















