Upgrade old iOS and Android apps to a single, scalable React Native codebase to save money, speed up releases, and make every feature feel like a climb. BYBOWU is an IT studio in the US that specializes in modernizing React Native apps and migrating brownfield and greenfield apps to a single high-speed stack. We mix product thinking with deep engineering—React Native, Expo EAS, TypeScript, and Swift/Kotlin modules—and give you predictable results: faster startup, fewer crashes, and more frequent releases. Our team builds end-to-end experiences with Next.js, Laravel, WordPress, SEO, ads, and AI-powered solutions, so your app and your growth engine work together.
Benefits of modernization with React Native
This isn’t a cosmetic refresh. It's an upgrade to how things work that gets bigger every sprint. Here’s what leaders gain from legacy app migration 2025 plans done right:
- One codebase, two platforms: iOS and Android release together—no more split roadmaps or duplicated bugs.
- Lower total cost of ownership: Consolidated engineering cuts maintenance and accelerates feature velocity.
- Performance tuned: Hermes engine, JSI/TurboModules, and selective native modules deliver near-native UX.
- Safer releases: Expo EAS + automated testing enable phased rollouts, OTA fixes, and faster recovery.
- Future-ready architecture: TypeScript-first, modular code, feature flags, and robust analytics/observability.
- Modern UX patterns: Smooth gestures, accessibility (WCAG 2.2), and component libraries for consistent design.
- Security by design: Keychain/Keystore storage, certificate pinning, SSO + MFA, and compliance-minded data flows.
Why now? Every month you spend fixing old code is a month your competitors can use to ship features that your customers will expect tomorrow. A long-lasting modernization includes architecture, delivery, and quality. We make the foundation stronger and fix the weak spots so you can move faster and more safely.
- Architecture: Feature-sliced structure, navigation patterns (React Navigation 7), and dependency hygiene.
- State and data: Redux Toolkit or Zustand plus React Query for robust caching, retries, and offline-first flows.
- Native bridges: Camera, biometrics, push notifications, deep linking, background tasks—stable and testable.
- DX and CI/CD: Expo EAS builds, code signing, GitHub Actions or Bitrise pipelines, OTA updates where compliant.
- Testing: Unit, integration, and E2E (Jest, RN Testing Library, Detox) with device farms for coverage.
- Analytics/observability: Sentry/Crashlytics, Segment/GA4, performance budgets, and release dashboards.
- Accessibility & i18n: Localization and multi-language support with vetted tone, glossary, and RTL readiness.
Our migration process for legacy iOS/Android apps
Decision-stage buyers need a plan, not platitudes. Here is our tried-and-true way to move to React Native without any problems: We plan for costs, risks, and expected performance gains. Set goals, features, and success metrics. Threat model and compliance mapping from the start. We keep old screens alive while new ones come out behind flags. Performance budgets are enforced for each release. Your team needs documentation, training, and playbooks. Check out our full list of services to see how mobile, web, and SEO work together to help your business grow. Migration is a chance to fix long-standing performance problems. We adjust the app's startup time, responsiveness, and reliability so that it feels faster and more stable.
- Cold-start reduction: Hermes, route-based code splitting, prioritized asset loading, and lightweight bootstrap.
- Smooth interactions: Reanimated 3, Gesture Handler, memoization, and list virtualization for large data sets.
- Data efficiency: Delta sync, backoff and retry strategies, background tasks, and offline-first queues.
- Stability: Crash-free sessions improvement via defensive coding, native module isolation, and proactive error boundaries.
- Monitoring & rollback: Real user monitoring, feature flags, and staged rollouts with automated rollback criteria.
Typical results: 25–50% faster cold starts, 20–40% fewer crashes, and materially smoother gestures on mid-tier devices.
Not every team can stop working on a project to rebuild it from scratch. We'll meet you where you are and pick the safest path: Replace screens slowly, keep features that are important for making money live, and lower the risk. This is great when legacy code is fragile or the user experience needs to be rethought. A national retailer's native apps were slow to start up and had features that didn't always work. We added React Native, rebuilt the most visited screens (home, rewards, and checkout), and used EAS with staged rollouts. Result: A 42% faster cold start, 28% fewer support tickets, and synchronized feature releases for iOS and Android in 12 weeks.
Healthcare field ops—offline-first rebuild
A field operations app needed reliable offline workflows and secure data handling. We built a new React Native app from scratch that has encrypted storage, background sync, and access based on roles. Results: Tasks were finished 35% faster, sessions didn't crash 99.4% of the time, and logs were ready for audits to help with compliance. Want to see more results? Check out the best parts of our portfolio. Pricing and timelines—no surprises. Every migration is different, but we'll make sure you know what's going to happen before we change a single line. You'll get a scope, milestones, and an investment range based on business KPIs after a short discovery.
- Typical timeline: 8–14 weeks for parity-focused brownfield; 12–20 weeks for full greenfield with redesigned UX.
- What’s included: audit, architecture, refactor/rebuild, native modules, testing, EAS setup, analytics, and phased releases.
- Optional: design system upgrades, localization, SEO-aligned web landing pages, and post-launch optimization sprints.
For ballparks and scenarios, see our pricing guide. We link spending to speed, stability, and customer results, which makes the ROI clear.
FAQs
Can my existing app be migrated to React Native?
Yes, in most cases. We look at your native features, third-party SDKs, and performance limits. A brownfield approach, which involves adding React Native and replacing screens one at a time, is good for many apps. If legacy code is too fragile, we suggest rebuilding it from scratch with a planned cutover date.
Will performance be worse than if everything was fully native? Not if it is built correctly. React Native gets almost native performance with Hermes, TurboModules, and some Swift/Kotlin modules. To keep interactions smooth, we profile early, plan for cold starts, and move heavy work off the UI thread.
How long does a migration take? The size of the project determines how long it will take, but most parity migrations take between 8 and 16 weeks. We begin with a pilot module to test the stack, and then we grow. You will have dashboards that show how much testing has been done, how well it is working, and how far along the rollout is.
What about built-in features and SDKs? We use or make native bridges for important features like the camera, biometric authentication, push notifications, maps, payments, and more. We also check third-party SDKs to make sure they work with React Native. If there isn't a bridge, we make one in Swift/Kotlin with stable tests and interfaces.
Do we need to change our backend? Not necessarily. React Native works well with REST and GraphQL APIs that are already there. We can add pagination, caching, or authentication improvements during the migration to make mobile performance and reliability better, but your core services can stay the same.
Ready to modernize—without messing up your roadmap?
We will review your app, suggest the safest way to move it, and give you a release plan in just a few days. No fluff—just a simple upgrade that your team can take care of. Request a free consultation today to modernize your app. You can email us at [email protected] or go to contact.