AI-Native Engineering

AI-Assisted Migrations

Migration to React Native

Adopt React Native fast. Keep production quality.

Adopting React Native used to mean choosing between a year-long rewrite and AI-generated code you can't maintain. We collapse that choice: custom AI agents do ~70% of the work, and the team that builds React Native owns the quality. Short timelines, production-grade, your app live throughout.

Book a consultation

How we can help

What you get

Agent speed. Expert quality.

Adoption in months, not years

Custom AI agents do ~70% of the work: screen inventory, UI migration, business logic, baseline tests. What used to be a 12-month rewrite lands in 3–4 months.

30% of the work, 100% of the quality

A managed engagement from the team that builds React Native. Engineers own architecture, review, and hardening on every screen we deliver.

Native-quality UI

Matched to your platform's look, feel, and responsiveness, with every screen benchmarked with Reassure. No visible difference during the transition.

Architecture before agents

Experts set the foundation before any agent writes a line: lean, best-practice React Native, not generated debt.

Greenfield or brownfield - we help you choose

Discovery ends with a data-backed recommendation, not a default. Brownfield keeps your app live, screen by screen on Rock; greenfield gives a clean architectural reset.

Priced per screen, not per line

Pricing tracks screens and complexity; per-line pricing rewards bloat. You know each phase's cost upfront and can stage the investment.

One codebase, every platform

Each migrated screen targets iOS, Android, and Web from a single codebase (~90% code sharing), extendable to TV and desktop.

Training and handover

Onboarding guides, workflows, and the migration skills we configure for your codebase. You own everything we build and run it without us.

Migration to React Native

Adopt React Native while you ship

Custom AI agents set the pace; the team that builds React Native owns the quality. Get a plan for adopting React Native quickly.

Get a migration plan

Scope → Build → Scale

Move from migration plan to rollout.

Scope

We map your problem, align on deliverables, and define success metrics. No surprises once work starts.

Start in weeks, not months

Fixed scope before work starts

1 WEEK

Build

Engineers ship with AI-native workflows from sprint one. Code, decisions, and ownership, not discovery decks.

3 Callstack engineers ship like 6

Impact visible before sprint two

1-12 MONTHS

Scale

Expand scope, add platforms, or hand off to your team. The stack, tooling, and raised bar stay with you.

You own everything we build

Move faster on the next launch

AS NEEDED

Case studies

What shipping at AI speed looks like

AI-Assisted Migrations

Architecture & Performance

Modernizing a Crypto Trading Platform With React Native and Self-Hosted OTA

increase in RN pages across the tracked page set

Architecture & Performance

AI-Assisted Migrations

AI-Driven QA & Testing

Migrating Questrade Edge Mobile to a Faster, More Scalable Architecture

33%

fewer re-renders across most features

AI-Assisted Migrations

Self-Hosted CI/CD Infrastructure

Migrating a Legacy React Native App to Expo for Faster Builds and Simplified Releases

faster builds after replacing Jenkins with EAS

Team Training

AI-Assisted Migrations

Architecture & Performance

Training HelloFresh Engineers to Build Production Apps With React Native

2.8x

increase in knowledge over 8 weeks (25% → 71% assessment scores)

AI-Assisted Migrations

End-to-End Product Development

Self-Hosted CI/CD Infrastructure

Migrating iOS and Android Apps to React Native for AutoZone

growth in mobile user base during the migration period

AI-Assisted Migrations

Feature Development

End-to-End Product Development

Modernizing 7Cup's React Native Codebase and Adding Platform Features

130%

increase in users post-upgrade

10 years of React Native → Now in your AI stack

Adopt React Native while you ship

Custom AI agents set the pace; the team that builds React Native owns the quality. Get a plan for adopting React Native quickly.

Get a migration plan

Why teams bet on Callstack

From billion-user apps to React Native core, this is why teams choose Callstack when they need to move fast and get it right.

Rocket ascending into a blue night sky with digital binary code forming its smoke trail.

10 years in React Native. Now shaping agentic engineering.

For a decade, we have helped define how teams ship with React Native. Now we are helping shape how they work with agents.

Founded in 2016 ·Backed by Viking Global Investors

React Foundation members. Core Contributors.

We are founding members of React Foundation and Core Contributors to React Native. You get direct access to people close to the decisions shaping the frameworks you use.

Open source since 2016. Our code runs in your app.

We contribute to React Native and maintain libraries across its ecosystem. Our code runs in apps used by millions of people every day.

Open Source Projects

39M+

Downloads / month

67K+

GitHub stars

300+

React Native commits

100+ Enterprise clients with 7B+ users.

We work with teams shipping at real scale. You get a partner used to high-stakes products, not learning on your roadmap.

Agent Conf. The conference for the Agentic era.

The conference we built for the shift from writing code to orchestrating agents.

Agent Conf

Gradient background blending white, light blue, and purple shades with smooth transitions.

Man wearing glasses and a Stanford sweatshirt speaking into a microphone during a presentation.

We are Codex Ambassadors.

We run meetups, workshops, and hands-on  sessions that help teams learn Codex  and apply it in real work.

Check Events

10 years in React Native. Now shaping agentic engineering.

For a decade, we have helped define how teams ship with React Native. Now we are helping shape how they work with agents.

Founded in 2016 ·Backed by Viking Global Investors

React Foundation members. Core Contributors.

We are founding members of React Foundation and Core Contributors to React Native. You get direct access to people close to the decisions shaping the frameworks you use.

Open source since 2016. Our code runs in your app.

We contribute to React Native and maintain libraries across its ecosystem. Our code runs in apps used by millions of people every day.

Open Source Projects

39M+

Downloads / month

67K+

GitHub stars

300+

React Native commits

100+ Enterprise clients with 7B+ users.

We work with teams shipping at real scale. You get a partner used to high-stakes products, not learning on your roadmap.

Agent Conf. The conference for the Agentic era.

The conference we built for the shift from writing code to orchestrating agents.

Agent Conf

We are Codex Ambassadors.

We run meetups, workshops, and hands-on  sessions that help teams learn Codex  and apply it in real work.

Check Events

Still have questions?

Let’s find the right path
for your product.

Whether you’re planning new work or unblocking an existing product, we’ll help you choose the right path forward.

Book consultation

How do you migrate to React Native without disrupting the native app?

We use a brownfield approach, introducing React Native as a module inside your app, so you can transition incrementally, without risking stability or breaking workflows.

How do you ensure native-quality performance after migration?

We focus on critical areas like startup time, navigation smoothness, and animation performance, applying platform-specific optimizations where needed.

How do you support teams during and after the migration?

We deliver technical trainings, workflow adjustments, and ongoing architectural guidance to ensure your teams can scale React Native confidently after initial adoption.

Can we migrate gradually, screen by screen?

Yes. Our approach is designed for gradual migration, allowing you to add new screens or features in React Native without rewriting the entire app at once.

How much of the work is done by AI agents versus engineers?

This is a managed engagement, not a script you run: roughly 70% custom AI agents, 30% expert engineering - and 100% of the quality on us. Agents handle screen inventory, UI migration, business-logic translation, and baseline tests; engineers own architecture, state, and performance, and review every screen before delivery.

How do you keep our code and data secure when AI agents do most of the work?

Our agents run under expert engineering oversight with full quality ownership, so every change is reviewed before it lands. The AI accelerates delivery; our engineers stay accountable for what ships.

Why not just use an AI migration platform directly?

Pure AI migration produces code bloat, web-style technology choices, and broken architecture - we've seen ~5% of an app's functionality generate hundreds of thousdands lines of code. Our agents are configured for your codebase, every output is reviewed by React Native experts, and we own the delivery outcome.

Can a migration this fast really be production quality?

Yes - speed and quality come from different places. Agents supply the pace; the people who build React Native supply the quality. Architecture is set before agents write code, every screen is expert-reviewed and benchmarked with Reassure, and each lands in production independently rollback-able.

Should we go greenfield or brownfield?

It depends on your app, and that's the point - we recommend, not push. Brownfield suits apps that must keep shipping: screens land incrementally, validated in production. Greenfield is often faster for smaller apps or codebases with unrecoverable technical debt. Discovery ends with a recommendation grounded in your codebase, not a default.

Migration to React Native

Adopt React Native while you ship

Custom AI agents set the pace; the team that builds React Native owns the quality. Get a plan for adopting React Native quickly.

We had been struggling with React Native application performance until we met Callstack.

Huỳnh Chí Hùng

Associate Director / MOMO

Open Source

Want to build it on your own?

We open-source the tools behind our delivery model.
Use them, fork them, or let us run them for you.

Check All Tools

Explore AI Infrastructure

React Native Brownfield

Incrementally move your iOS and Android apps to React Native without breaking

516

stars

Agent Skills

Callstack’s best practices on React Native performance optimization, upgrading, CI workflows, and brownfield migrations

1374

stars

React Native Community CLI

Command line tools to help you build React Native apps

10297742

downloads / month

React Native Builder Bob

Simple set of CLIs to scaffold and build React Native libraries for different targets

1525894

downloads / month

Rock

Modular toolkit for teams building React Native apps

688

stars

Insights

Worth your time, by engineers.

Explore Insights

Aug 27

Article

React Native in .NET MAUI: A Practical Brownfield Integration Guide

This article walks through how we embedded React Native inside a .NET MAUI application using a brownfield setup. It covers the packaging layer, lifecycle wiring on iOS and Android, navigation through MAUI Shell, and shared state between the MAUI and React Native runtimes.

Aug 3

Article

Migration to React Native in 2026 Starts With a Delivery Question

This article helps mobile teams choose between brownfield and greenfield React Native migration. It explains how each approach shifts risk across continuity, native dependencies, delivery pressure, verification, and architecture ownership, and introduces a checkpoint-based path for teams that want to test a greenfield rebuild before committing. It also shows where AI can help and what still needs human control.

Jul 8

Article

How we made Hybrid iOS apps compile 39% faster with React Native Brownfield

React Native Brownfield 3.10 brings iOS prebuilts into the packaging flow, removing a major compile step from hybrid app builds. This article explains how the integration works, what changed under the hood, and what our benchmark results show for React Native and Expo projects.

Jun 11

Article

AI-Assisted React Native Migration for TV: Lessons From Zattoo

Zattoo started its React Native TV migration before today’s AI-assisted workflows became common. Their story shows where AI can now support similar migrations, from onboarding and refactoring to testing and platform-specific implementation work.

Jun 3

Article

AI-Supported Brownfield Migration to React Native

Brownfield migration is rarely slowed by the rewrite itself. The real cost sits in setup, requirements capture, native integration, and validation. This article shows how an AI-supported workflow reduces that work from weeks to days while keeping engineering review in the loop.

Mar 31

Article

Brownie: A Type-Safe Shared-State Workflow for Brownfield React Native

For teams embedding React Native into existing native apps, Brownie reduces state-management glue code at the integration boundary. One TypeScript schema drives shared state across React Native, iOS, and Android with a workflow built for production use.

Mar 24

Article

From Brownfield Complexity to AI-Supported React Native Migration

Brownfield migrations often fail due to ordering and integration gaps, not framework limits. This article explains how an AI-supported workflow helps enforce correct sequencing across packaging, startup, and runtime validation.

Mar 13

Article

Handling Navigation in React Native Brownfield Apps

Navigation between React Native and existing native screens can be difficult in brownfield apps. This guide shows how to define a navigation contract, generate native delegates, and connect both layers using @callstack/brownfield-navigation.

Feb 26

Article

Announcing: React Native Brownfield v3 with Expo Config Plugin

Moving a large native app to React Native rarely happens in one rewrite. React Native Brownfield v3 combines Expo with an artifact-based packaging approach, so you can ship React Native screens inside your existing app without destabilizing your product.

Jan 20

Article

Introducing Brownie: Type-Safe Shared State for React Native Brownfield Apps

Brownie is a new shared state library designed for React Native brownfield applications. It addresses a common pain point in mixed native and React Native codebases: keeping state consistent without building and maintaining custom Turbo Modules. With Brownie, teams define their state once in TypeScript and generate matching native types automatically. The article introduces the core ideas, shows how the workflow fits into real brownfield apps, and outlines what’s included in the iOS alpha release.

Apr 28

Article

Powering Native Apps with React Native Brownfield

This article introduces the brownfield approach, explaining how it allows you to bring React Native into existing native apps without starting from scratch. It then covers how our library, React Native Brownfield, simplifies this process by embedding React Native screens into native apps, and provides an overview of its structure and key features.

Sep 6

Article

iOS Brownfield App With React Native in an Easy Way

Integrating React Native into an existing iOS app doesn't have to be complicated. This guide walks through how to add React Native screens to a native codebase incrementally, with practical tips to navigate between native and React Native views seamlessly.

Dec 27

Article

Why Is It Important to Always Run The Latest Version of React Native?

Keeping your React Native app up to date is crucial for accessing new features, performance improvements, and security fixes. While upgrading can be challenging, tools like React Native Upgrade Helper and align-deps simplify the process of applying changes and managing dependencies.

Nov 18

Article

Why Brownfield Development With React Native Is Worth Your Attention

Migrating to React Native doesn't have to disrupt your existing apps. We walk through how to introduce React Native incrementally using a brownfield approach, allowing you to validate early technical risks before scaling up.

Feb 6

Article

Stripe React Native Migration Function by Function - Tipsi Migration Guide, Part 3

This article dives into the details of migrating each payment function from tipsi-stripe to the official stripe-react-native SDK. It covers card components, accepting payments, tokens, Apple Pay, Google Pay, and provides a real-world migration example.

Feb 8

Article

Stripe React Native: the Most Common Questions - Tipsi Migration Guide, Part 5

Migrating from tipsi-stripe to the official Stripe React Native SDK? This guide answers common questions about feature parity, incremental migration, Expo support, and more to help you make the switch smoothly.

Dec 6

Article

Stripe React Native Configuration - Tipsi Migration Guide, Part 2

Migrating from tipsi-stripe to the official Stripe React Native SDK? This guide walks through the key steps to remove tipsi-stripe, add stripe-react-native, and initialize the new library using the StripeProvider component.

Oct 1

Article

Simplify Your iOS Brownfield Integration With RootViewFactory

Integrating React Native into existing iOS apps can be tricky, especially when enabling the New Architecture. RootViewFactory simplifies this process, making it easier to create React Native views in brownfield apps without verbose setup or refactoring.

Nov 3

Article

Migrating a React Native Library to the New Architecture

Migrating a React Native library to the New Architecture doesn't have to be daunting. This guide walks through the key steps, from writing TypeScript specs to extending generated interfaces, with helpful resources and examples from recently migrated libraries.

Apr 19

Article

Migrating React and Native Apps To React Native - Everything You Need To Know

Migrating native or React apps to React Native doesn't have to be a complete rewrite. We walk through the key differences between greenfield and brownfield approaches, and share best practices for incrementally introducing React Native while maintaining your existing apps.

Nov 28

Article

How to Upgrade React Native in a Brownfield Application

Upgrading React Native in a brownfield app can be complex, with challenges like dependency conflicts and breaking changes. This guide walks through the process step-by-step, from aligning dependencies to updating native code for iOS and Android. It also covers common pitfalls and tips to make the upgrade smoother.

Feb 7

Article

How to Not Break Your App After Migrating From Tipsi Stripe to Stripe React Native - Migration Guide, Part 4

Migrating from Tipsi Stripe to Stripe React Native can be daunting, but following best practices helps ensure a smooth transition. This guide shares key steps like writing end-to-end tests, building your app frequently during migration, and setting up crash reporting to catch any issues early.

Nov 8

Article

How to Migrate From Tipsi Stripe to the Stripe React Native SDK - Migration Guide, Part 1

Migrating from the unmaintained tipsi-stripe library to the official stripe-react-native SDK doesn't have to be painful. This guide walks through the key differences, new features, and steps to upgrade your React Native app to the latest payments integration.

Nov 25

Article

How to Integrate React Native With an Existing App

Integrating React Native into an existing app doesn't have to be daunting. We walk through a practical example of adding React Native to the open-source Mastodon iOS and Android apps, sharing step-by-step instructions to get you started.

Sep 6

Article

Developing an Android Brownfield App With React Native in an Easy Way

Integrating React Native into an existing Android app doesn't have to be complicated. This guide walks through how to add React Native screens to a native Android codebase in a few simple steps using the react-native-brownfield library.

Jul 24

Article

Adding React Native to an Existing Flutter App

Adding React Native to an existing Flutter app is possible, though it requires integrating two cross-platform runtimes. We walk through the key steps to embed React Native views, set up popular libraries, and explore potential use cases for incrementally migrating or extending Flutter apps with React Native.

May 16

Podcast

You Don’t Need a Rewrite, You Need React Native Brownfield

Discover how modern React Native Brownfield integration enables cross-platform power in native apps, without rewriting from scratch.

Jun 14

Podcast

Migration to React Native

The 13th episode of React Universe On Air (formerly known as The React Native Show) is fully focused on migrating from different technologies to React Native, the two most popular approaches to this process (greenfield and brownfield software development), and our state-of-the-art brownfield approach.

Jan 13

Podcast

Lessons from Shopify's Migration to React Native with Mustafa Ali

Learn how Shopify's migration to React Native led to 86% code unification, reduced build times, and seamless feature parity across platforms.

Jun 8

Podcast

Brownfield Development With React Native

Learn how to tackle brownfield development with React Native, explore real-world challenges, and discover the React Native Brownfield library.

August 27, 2026

Event

Adoption of Brownfield in React Native

Artur Morys-Magiera will explain how teams can adopt React Native incrementally inside existing native applications.

October 9, 2026

Event

React Native Brownfield Deep Dive: How RN Moves Into Native Applications

Artur Morys-Magiera will explain how React Native can move into an existing native app without forcing a big-bang rewrite.

August 18, 2026

Event

Agentic AI in the Wild - Boston Dev Community Meetup

Join us in Boston on August 18 for an evening focused on a question most teams hit quickly with AI agents: how do you make them dependable once they leave the prototype phase and start touching code, workflows, and delivery timelines?

May 5, 2026

Event

KLJS x React Universe Meetup, Kuala Lumpur

Join Callstack and Ryt Bank on May 5 in-person for a React Universe meetup with practical talks for engineers working with React and React Native in production.

April 27, 2026

Webinar

From Native to React Native for TV: The Zattoo Case

Learn why and how Zattoo moved from native TV apps to React Native, what changed for their team, and what it takes to scale across multiple platforms efficiently.

April 2, 2026

Webinar

AI-Assisted Migrations to React Native: From Months to Days

Reduce migration time from months to days by using AI in real React Native workflows. Learn when to migrate incrementally and when starting fresh is the better option.

April 23, 2026

Event

State of Brownfield in React Native

A practical look at Brownfield React Native adoption in mature native apps, architecture, tooling, and real-world tradeoffs.

November 17, 2025

Event

Vega Developer Meetup

Learn how to integrate React Native into Android TV apps at the Vega Developer Meetup. Workshop, roadmap, and community talks, live in Munich.

November 5, 2025

Webinar

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.

October 8, 2025

Event

React Everywhere: Bringing React Into Native Apps

Most teams use React on the web but still rely on native code or WebViews in their mobile apps. This talk explores how React Native can replace WebViews with minimal effort, allowing React to power both web and mobile.

August 5, 2025

Webinar

How to Gradually Migrate From React Native Community CLI to Expo

Learn how to migrate your React Native Community CLI app to Expo incrementally, with minimal risk. A recording of a webinar hosted by Callstack & Expo.

June 24, 2025

Event

Brownfield Incremental React Native Adoption x Rock

Learn how to smoothly adopt React Native in your existing apps using Callstack’s Rock for easier setup, faster deployment, and seamless integration.

June 24, 2025

Event

React Universe Meetup, New York

Join us in NYC or online for React Universe Meetup: tech talks, real-world insights, and networking with React Native devs. June 24, 2025.

May 27, 2025

Webinar

Adding React Native to iOS and Android Apps Has Never Been Easier

Learn how to easily add React Native to your iOS and Android apps with a modern brownfield setup powered by Callstack’s open-source tooling.

March 13, 2025

Webinar

Using React Native in Existing Apps for Faster Cross-Platform Features

Learn how to use React Native in existing apps to speed up cross-platform development without a full rewrite. Watch the expert-led webinar now.

Sunbelt Computer Software

PL/B Language Development and Support

Adopt React Native fast. Keep production quality.

Agent speed. Expert quality.

Adoption in months, not years

30% of the work, 100% of the quality

Native-quality UI

Architecture before agents

Greenfield or brownfield - we help you choose

Priced per screen, not per line

One codebase, every platform

Training and handover

Adopt React Native while you ship

Move from migration plan to rollout.

Scope

Build

Scale

What shipping at AI speed looks like

Modernizing a Crypto Trading Platform With React Native and Self-Hosted OTA

Migrating Questrade Edge Mobile to a Faster, More Scalable Architecture

Migrating a Legacy React Native App to Expo for Faster Builds and Simplified Releases

Training HelloFresh Engineers to Build Production Apps With React Native

Migrating iOS and Android Apps to React Native for AutoZone

Modernizing 7Cup's React Native Codebase and Adding Platform Features

Adopt React Native while you ship

Why teams bet on Callstack

39M+

67K+

300+

39M+

67K+

300+

Let’s find the right path for your product.

How do you migrate to React Native without disrupting the native app?

How do you ensure native-quality performance after migration?

How do you support teams during and after the migration?

Can we migrate gradually, screen by screen?

How much of the work is done by AI agents versus engineers?

How do you keep our code and data secure when AI agents do most of the work?

Why not just use an AI migration platform directly?

Can a migration this fast really be production quality?

Should we go greenfield or brownfield?

Adopt React Native while you ship

Want to build it on your own?

React Native Brownfield

Agent Skills

React Native Community CLI

React Native Builder Bob

Rock

Worth your time, by engineers.

React Native in .NET MAUI: A Practical Brownfield Integration Guide

Migration to React Native in 2026 Starts With a Delivery Question

How we made Hybrid iOS apps compile 39% faster with React Native Brownfield

AI-Assisted React Native Migration for TV: Lessons From Zattoo

AI-Supported Brownfield Migration to React Native

Brownie: A Type-Safe Shared-State Workflow for Brownfield React Native

From Brownfield Complexity to AI-Supported React Native Migration

Handling Navigation in React Native Brownfield Apps

Announcing: React Native Brownfield v3 with Expo Config Plugin

Introducing Brownie: Type-Safe Shared State for React Native Brownfield Apps

Powering Native Apps with React Native Brownfield

iOS Brownfield App With React Native in an Easy Way

Why Is It Important to Always Run The Latest Version of React Native?

Why Brownfield Development With React Native Is Worth Your Attention

Stripe React Native Migration Function by Function - Tipsi Migration Guide, Part 3

Stripe React Native: the Most Common Questions - Tipsi Migration Guide, Part 5

Stripe React Native Configuration - Tipsi Migration Guide, Part 2

Simplify Your iOS Brownfield Integration With RootViewFactory

Migrating a React Native Library to the New Architecture

Migrating React and Native Apps To React Native - Everything You Need To Know

How to Upgrade React Native in a Brownfield Application

How to Not Break Your App After Migrating From Tipsi Stripe to Stripe React Native - Migration Guide, Part 4

How to Migrate From Tipsi Stripe to the Stripe React Native SDK - Migration Guide, Part 1

How to Integrate React Native With an Existing App

Developing an Android Brownfield App With React Native in an Easy Way

Adding React Native to an Existing Flutter App

You Don’t Need a Rewrite, You Need React Native Brownfield

Migration to React Native

Lessons from Shopify's Migration to React Native with Mustafa Ali

Brownfield Development With React Native

Let’s find the right path
for your product.