Rozenite, RN AI, Node-API, Sandbox, Brownfield Guide, and RNEF: We Shipped A LOT

Hey,

It’s Michał. July was busier than ever. In fact, we’ve got so many updates, I’ll keep this short. Before we dive in, one important update: we’ve locked in 50 tickets to React Conf 2025 just for our readers. You’ll find all the details below. Now let’s talk about all the news.

Community highlights

• Precompiled React Native for iOS: Faster builds are coming in 0.81: Compiling the React Native library and its dependencies has always been a significant contributor to build time. This problem was solved years ago on React Native for Android by using a precompiled version of the library by default. Now it comes to iOS with React Native 0.81 and Expo SDK 54
• React Compiler getting ready for stable release: The React Compiler has been in the RC phase for a while, and recent extensive updates to the documentation hint that there may be a stable release coming soon.
• Next.js 15.4: Turbopack, Next.js’s own bundler, has reached 100% compatibility with the framework’s integration test suite for builds (previously it hit that mark for development), making it worth trying instead of Webpack. The core team also shares their plans for the v16 release.
• Reanimated 4 Stable Release — the Future of React Native Animations: CSS animations and transitions (with JS-flavored syntax) are finally available with the v4 of Reanimated, now stable. The library has also extracted worklets to a separate package (so you can use them without Reanimated) and introduced a few changes, e.g., to the spring animation defaults.
• Google confirms it's 'combining' Chrome OS and Android into a single platform: Starting from November, Chrome OS will be merged into Android, which aligns with the Android 16 release showcasing more desktop-themed features on that platform.
• The many, many, many JavaScript runtimes of the last decade: This last decade has seen an inundation of new JavaScript runtimes (and engines in equal measure), enabling us to run JavaScript in all manner of contexts with precise fitness for the task. A fascinating read going through the language spread to the Cloud, the edge, Smart TVs, mobile devices, and even microcontrollers.

Callstack Incubator highlights

React Native AI

Mike and Szymon Rybczak are working hard on making the on-device LLM processing as simple as calling Vercel’s AI SDK, blurring the lines between on- and off-device AI processing.

While the React Native AI project started with MLC driving models, it’s now heading towards Foundation Models dropped by Apple with iOS 26 release (and Android with Gemini Nano) that surprise us with great performance and capabilities such as structured output, tool calling, embeddings, all powered by GPU.

React Native Brownfield

Lately, Callstack's been doing a lot of “brownfield” work for our clients, who want to integrate React Native into their iOS and Android apps incrementally.

So, together with Burak Güner and Hur Ali, we sat down and wrote a book on how you can do it, with our Packaging Approach and the React Native Brownfield library. You can get the book for free here.

React Native Node-API

We’ve already let you know about the React Native Node-API project in the June release. Now, we have some follow-up articles for you about building and running Node-API modules in React Native, and a deep-dive into how Node-API works in React Native. Give them a read if you’d like to build cross-platform and cross-framework modules that run in React Native and NativeScript.

Rozenite

For the past few weeks, Szymon Chmal had been creating a missing plugin system for the React Native DevTools. And he delivered! Turned out it’s not even necessary to hack DevTools. He was able to reuse internal communication protocols and build on top of them.

Rozenite, as that’s the rocky name of the plugin framework, ships with long missing tools, such as Redux DevTools, TanStack Query DevTools, Network Inspector, MMKV, and there’s more coming. What’s most important is that you can build your own plugins with Rozenite (and people already do). Bringing your favorite web dev tools to React Native has never been easier.

React Native Sandbox

There are never enough releases! Aliaksandr Babrykovich, who joined Incubator team briefly over last the 2 months, was busy shipping a new library: React Native Sandbox. It’s resulted from a proof of concept for running multiple instances of React Native together in a single native application, without interfering with each other.

The library allows you to isolate particular components registered with React Native’s AppRegistry and provides these components with an API to message the host app back and forth. Focused on the security of running isolated code on different JavaScript runtimes, but in the same app, it opens the doors for more secure module federation approaches or AI agent-driven workflows.

React Native Enterprise Framework

In the land of build tools for React Native, RNEF experiments with uploading ad-hoc builds for S3 so you can single-click (ok, there are two clicks) install iOS apps on your device from a URL. This is a convenient workflow you may know from Fastlane or EAS, soon available in RNEF without using any Ruby under the hood.

We’ve also started teasing a big change that’s coming to the framework. Can you guess what it’s going to be?

Core Contributions

I’d also like to feature a few contributions our engineers (not even currently in the Incubator!) provided for the React Native core project. React Native Modal got some special love from Oskar, who contributed allowSwipeDismissal prop.

Maciej Jastrzębski’s been contributing to improved accessibility.

Piotr Trocki had his contribution to Hermes–React Native integration, which allows resetting the timezone cache, which comes in handy when a timezone or system settings change while your app is running. Currently, it’s available through a timezone-hermes-fix package, and we hope to contribute that to the more popular React Native Localize package to be broadly available as useCurrentTimezone hook.

Guides

In case you missed it in the long list of Incubator highlights, we released a new guide: Incremental React Native Adoption in Native Apps. It’s meant for iOS and Android teams who want to experiment with React Native gradually, without slowing delivery or rewriting the whole app. It includes:

• A side-by-side look at legacy vs. modern integration approaches
• How the Packaging Approach and React Native Brownfield library simplify setup
• Step-by-step walkthroughs for iOS and Android
• Real-world migration insights from the Callstack team

The bottom line? This guide will help you bring React Native into production safely and incrementally.

Blog

I’ve already mentioned some of the July articles in the Incubator highlights, so let me just list the remaining ones here:

• Exploring Fibers: Cooperative Multitasking and Lock-Free Task Execution by Mariusz Pasiński: This third installment (read part 1 here, and part 2 here) in our performance series focuses on building a cooperative, fiber-based task scheduler. We explore what fibers are, how they relate to coroutines, and how to organize tasks using atomic counters instead of traditional locks. You’ll learn how to avoid blocking, manage dependencies across tasks, and profile execution with Tracy. The concepts apply across languages and runtimes, offering a foundation for designing lock-free systems that scale efficiently on modern CPUs.
• Performant and Cross-Platform Shimmers in React Native Apps by Kewin Wereszczyński: react-native-fast-shimmer brings high-performance shimmer effects to React Native, offering developers a modern alternative to spinners. Built with SVG and Reanimated, it enables fluid, synchronized animations with minimal overhead, even when rendering many placeholders at once. It is designed for customization and easy integration with Expo, bare React Native apps, as well as other platforms.
• On-Device Apple LLM Support Comes to React Native by Mike Grabowski: Apple’s on-device LLM is now available in React Native, enabling developers to build private, fast, and offline AI features powered by Foundation Models. This preview release supports text generation, streaming, structured outputs, and first-class support for Vercel AI SDK. A stable version is planned for release alongside iOS 26 later this fall.

Podcast and talks

• React Universe On Air Structure Monorepo for Speed, Scale & Sanity: Discover how Nx empowers teams to build and scale monorepos without losing their sanity, from selective testing to AI-powered workflows.‍
• Observability for Application Deployments by Pepijn Sanders (HelloFresh): Discover practical observability techniques to pinpoint and fix slow deployments, optimize global performance, and deliver faster apps.‍
• Brownfield Incremental React Native Adoption x RNEF by Michał Pierzchała: Learn how to smoothly adopt React Native in your existing apps using Callstack’s RNEF for easier setup, faster deployment, and seamless integration.‍
• Elevate React Native Observability With OpenTelemetry by David Rifkin (Embrace): Learn how to leverage OpenTelemetry to gain deeper, real-time insights into your React Native apps and significantly improve user experience.

Webinars and live streams

• How to Gradually Migrate From React Native Community CLI to Expo webinar: Learn how to migrate your React Native Community CLI app to Expo incrementally, with minimal risk. Hosted by Callstack & Expo.
• Live Dev Session: Rozenite DevTools Plugins Framework, Precompiled React Native for iOS, TanStack DB 0.1 recording and summary thread
• Live Dev Session: Reanimated 4, Worklets, React Native Screens recording and summary thread
• Live Dev Session: Node-API, Wallets & Worklets in React Native recording and summary thread
• Build High-Performance Modules in React Native With Node-API live stream recording and summary thread
• Live Dev Session: Unistyles 3.0, SSR With Hermes & Expo SDK 52 recording and summary thread

Future direction

We’re not stopping, and in August, our team, as always, is focusing on multiple initiatives:

• Push the on-device AI topic to the limits prior to iOS 26 launch
• Add some missing iOS 26 functionality to core React Native
• Explore integrating React Native Sandbox with Module Federation in Re.Pack
• Release Re.Pack 5.2
• Announce an important change to RNEF (and work towards TV support, ad-hoc uploads, and CNG)
• Visualization tool for React Native Legal (it’s really cool)

Last but not least, we’ll need to prepare the Keynote for React Universe Conf; there’s gonna be a lot of content from our team, stay tuned!

Upcoming events

React Universe Conf

The full React Universe Conf agenda just dropped, and it’s stacked. Joining the speaker lineup are:

• Nicola Corti and Riccardo Cipolleschi from Meta
• Anisha Malde from Amazon
• Rene Eichhorn from Zalando
• Ohans Emmanuel from HelloFresh
• Plus our very own Szymon Chmal

Other highlights:

• A Vercel AI SDK v5 workshop on Day 0, hosted by Matt Pocock. Workshop + conf bundle are available at a discount (or sign up for the workshop solo). Here’s a preview of what’s coming:

• React Native 10th Anniversary Bash on Day 2 🎉 Special guests, surprises, and maybe even some throwbacks:

Book your spot at and see you in September!

React Conf 2025

As a co-host of React Conf 2025, we’ve reserved 50 tickets for our newsletter readers. Click here to buy your React Conf ticket and join the world's leading React event on October 7 and 8 in Las Vegas.

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That’s a wrap on July! We’ll be back next month, with more tools, more updates, and a front-row seat at React Universe Conf. Am I seeing you in Wrocław this September? I hope so!

Michał