---
title: "Scaling React Native at Zalando: How Brownfield Migration Paid Off"
description: "Discover how Zalando scaled React Native across a massive e-commerce app, from internal buy-in to brownfield rollout, and what they learned."
url: https://www.callstack.com/events/scaling-react-native-at-zalando-lessons-from-brownfield-migration
updated: 2026-10-24T08:39:22.232Z
---

# 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.

_Webinar · 11/5/2025, 5PM-6PM [CET] · Online · Recording: 01:16:20 · Category: Brownfield_

Organizer: Callstack & Zalando

Speakers: Mike Grabowski (CEO & Founder @ Callstack), Maciej Jastrzębski (Software Engineer @ Callstack), Ghasem Bakhtiari (Sr. Principal Software Engineer @ Zalando), René Eichhorn (Senior Software Engineer @ Zalando), Jakub Stadniczuk (New Business @ Callstack)

[Watch the recording](https://www.youtube.com/watch?v=eH2zlBprK1k)

Watch the full webinar replay to see how Zalando’s engineers structured their [brownfield migration](https://engineering.zalando.com/posts/2025/10/accelerating-mobile-app-development-at-zalando-with-rendering-engine-and-react-native.html) 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](#yt-time=00:07:39), shared logic, and a unified platform experience. With an established internal framework, the [Rendering Engine](#yt-time=00:08:02), 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](#yt-time=00:14:31), open communication, and a strong proof of concept. A [POC built in 15 days](#yt-time=00:20:01) 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](#yt-time=00:18:32): 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](#yt-time=00:45:51) 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](#yt-time=01:04:25): 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](#yt-time=01:05:15), 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.