AI-Native Engineering

AI-Assisted Migrations

AI-Assisted Migrations

Execute complex migrations at agent speed.

We move teams off legacy systems without the cost and drag this work used to carry. AI-native workflows make complex migrations easier to plan, execute, and justify.

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AI-Assisted Migrations

Why migrate with Callstack

Move legacy work at agent speed.

We choose the greenfield or brownfield path that gets you to the new stack fastest, then use AI-native workflows to plan, validate, and execute the migration.

Move off legacy faster.

Replace architectures that slow delivery and make change harder.

Choose the right migration path.

Use a greenfield or brownfield migration approach based on which path gets you there fastest.

Reduce migration risk.

AI-native workflows improve planning, validation, and execution without giving up engineering control.

Build faster after migration.

A stronger foundation makes future delivery easier, faster, and cheaper.

Services

Move to the stack that fits next.

Technology Migrations

Migration to React Native

Move iOS and Android apps off separate native codebases onto one cross-platform stack, with the same product shipping to both stores from one codebase.

Migration to Self-Hosted Infrastructure

Move builds, CI/CD, and delivery off hosted platforms onto hardware you own, with full control over cost, security, and operations.

Migration to Modular Architecture

Break a monolithic app into independently deployed mini-apps that let engineering teams ship in parallel.

Migration to Expo

Move to Expo's managed workflow and EAS infrastructure. Faster builds, simpler releases, and full access to the modern React Native ecosystem.

Migration to Next.js

Move legacy React or SPA apps onto Next.js, adding server rendering, streaming, and edge delivery to the React stack.

React Native Modernization

Migration to New Architecture

Move React Native apps to the New Architecture (Fabric, TurboModules, and JSI), unlocking faster UI and synchronous native calls.

React Native Upgrades

Upgrade to the latest React Native release, patching security vulnerabilities and bringing the app up to date with new features and supported libraries.

UX Modernization

Improve high-impact journeys without rewriting the whole app, using product data, staged rollout, and real-device validation.

AI-Assisted Migrations

Migrate to a new stack with agents.

Send us the current stack and where you want to land. We'll come back with the migration path and the timeline.

Get my 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

Manifesto

When the way software is built changes, 
we help companies adopt it.

AI-native teams run on a system, not only on tools. Agents move the work forward. Experts make the calls that shape the outcome.

Learn Callstack Delivery Model

Case studies

What shipping at AI speed looks like

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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

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AI-Assisted Migrations
Self-Hosted CI/CD Infrastructure

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

6x

faster builds after replacing Jenkins with EAS

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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)

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AI-Assisted Migrations
End-to-End Product Development
Self-Hosted CI/CD Infrastructure

Migrating iOS and Android Apps to React Native for AutoZone

2x

growth in mobile user base during the migration period

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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

Migrate to a new stack with agents.

Send us the current stack and where you want to land. We'll come back with the migration path and the timeline.

Get my 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
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

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
Re.Pack

A webpack-based toolkit to build your React Native application with full support of webpack ecosystem

111317
downloads / month
Reassure

Performance testing companion for React and React Native

1438
stars

Insights

Worth your time, by engineers.

Explore Insights
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
No items found.
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May 5, 2026
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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.
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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.
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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.
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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.
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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.
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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.
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August 5, 2025
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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
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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.