React Native Brownfield
Incrementally move your iOS and Android apps to React Native without breaking
Tooling for introducing React Native into existing native apps incrementally.
What you get
Every native customization audited and mapped to a config plugin, prebuild step, or replacement.
Custom native code preserved through plugins instead of manual pod and gradle edits.
Builds, signing, and store submission automated end to end.
expo-updates configured with channels, staged rollouts, and rollbacks.
Legacy pipeline complexity replaced with a faster, smaller setup.
Your engineers leave fluent in the Expo workflow, not dependent on us.
How we work together
Our senior engineers join your team to ship features, guide technical decisions, and strengthen delivery.
We take agreed work from technical planning to release, with clear responsibilities and progress you can see.
We address a performance, migration, or infrastructure challenge, or run training around your team’s needs.
Case studies




Migration to Expo
We move the app to Expo and prove the speed difference in your own pipeline.
We had been struggling with React Native application performance until we met Callstack.

We’ll connect you with the right expert within 24 hours.
Still have questions?
Almost always. Config plugins and prebuild cover the vast majority of native customizations; the assessment flags the rare exceptions before work starts.
We replace it with a maintained equivalent, wrap it in a config plugin, or contribute the fix upstream - in that order of preference.
Both work. EAS is the fast default; self-hosted fits cost and compliance constraints. We model the economics for your release volume.
Low, run properly: the old pipeline keeps shipping until the Expo one is proven in parallel. No big-bang cutover.
Small apps in days with agent-assisted execution; complex native setups in weeks. The assessment gives you a real number.
Teams typically see dramatically faster builds versus legacy CI - one client cut build times 6x after replacing Jenkins with EAS.