React Native Evals, Expo SDK 55, and WebAssembly in Hermes

Hey,

It’s Michał with a bunch of updates from React Native community and Callstack Incubator in February and early March: new Expo SDK, State of React Native 2025 survey results, Evals for AI writing React Native, and many more.

Let’s jump right in!

Community highlights

• Expo SDK 55: This one comes with React Native 0.83, new native features in Expo Router (Zoom transition, Stack.Toolbar API, dynamic colors), tools for AI agents (expo/skills), and 75% smaller OTA diffs thanks to Hermes bytecode diff support. The legacy expo-av module has been removed and replaced by expo-video & expo-audio.
• WebAssembly Comes to Hermes: There is a new way to integrate C/C++, Rust, and more into your React Native app. It’s powered by native WebAssembly support in Hermes with the ability to precompile WASM to Hermes bytecode. Tzvetan is also teasing hermes-node as a CLI compatible with Node.js but running Hermes instead of V8. The team is cooking.
• Sparkling - Unlocks Lynx at TikTok Scale: ByteDance introduced Lynx last year as a framework-agnostic alternative to React Native. Until now, there was no straightforward way to bootstrap a new Lynx app from scratch (sic!). Sparkling aims to change that by providing the tooling the Lynx ecosystem has been missing, it’s like Expo for React Native. Łukasz from our podcast team posted a longer article on his Sparkling explorations, check it out.
• Google is expanding billing choice on Google Play: Google Play introduced alternative billing systems, effectively cutting fees to 15–20% for apps and 10% for subscriptions. What’s more, there’s a new Registered App Stores program for easier installation flow for alternative Android app stores (a.k.a sideloading) that meet certain quality and safety benchmarks.
• State of React Native 2025: The results are in, showing New Architecture at 80% adoption rate, more usage of native navigation primitives and Expo Router, a shift towards Tailwind-style utility classes for styling instead of relying on component libraries, more React Native Skia usage, and not that many developers complaining about the direction the project is going or that building with React Native is overly complex (it got way easier lately, hasn’t it?).

Callstack Incubator highlights

React Native Evals

Ever wondered which model works best with React Native by default? Now you don't have to. Our team shipped AI evals for React Native apps. We start with 43 common scenarios right now across animations, state management, navigation, and we have many more coming in the pipeline.

Apart from overall results and top 3 models, you’ll see token usage and API cost, so you have more dimensions to compare. We’re going to re-run these evals once in a while, so stay updated!

‍https://rn-evals.vercel.app

React Native Grab

You know the struggle of steering an LLM for UI changes. It often turns into full project exploration just to tweak a single wording. To make it easier for you, Szymon built a small utility that lets you select an element and copy its location, so an LLM can make surgical changes with minimal tokens. It’s like React Grab but for mobile apps, try it.

React Navigation

For React Navigation 8, Satya is experimenting with 2 things:

• Using React.Activity (will replace experimental freeze)
• Unmounting inactive screens entirely

It's a bit tricky because navigators can be nested. But hopefully it'll work out.

Agent Device

There are a few new things that landed in agent-device since our last update, most notably: native logging, TV support, snapshot (and soon screenshot) diffing, config through a file, and many more. We also crossed 1.1k stars on GitHub, thank you 🙌.

React Native Brownfield

Artur, together with Hur, prepared a new version of React Native Brownfield for you. This one is pretty special as it comes with:

• one-line Expo support with Expo Config Plugin
• brownfield CLI
• postMessage API
• Brownfield Navigation

In a future minor release, the team is also working on Android support for Brownie, our type-safe brownfield state management library.

React Native Sandbox

Aliaksandr found some time lately to finish the React Native Sandbox library by enhancing it with Android support. You can now run isolated JS code inside your React Native app, with guarantees for it not to break your main JS runtime. It’s a pretty powerful abstraction you can build on top of.

React Native core contributions

• Add core Yoga support for calc(): a proposal from Kamil for native CSS calc support for Yoga layout engine. This is a pre-requisite for this common CSS feature to work in React Native. It started as a big change to Yoga, but thanks to Nick from the core team we’re able to scope it as a smaller diff to the layout engine without impacting performance, and move more of the implementation to the React Native core (PR there landing soon).

Blog

• Handling Navigation in React Native Brownfield Apps by Hur Ali: 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.
• Announcing React Native Evals by Mike Grabowski, Lech Kalinowski, Piotr Miłkowski, Artur Morys-Magiera & Michał Pierzchała: React Native Evals is a new open-source benchmark from Callstack that evaluates how coding models implement real React Native tasks. The suite ships with 39 evals across animation, async state, and navigation categories, covering libraries like Reanimated, TanStack Query, Zustand, and React Navigation.
• Keeping Screens Visible With <Activity mode="hidden"> by Satyajit Sahoo: <Activity mode="hidden"> can reduce unnecessary work by unmounting effects for inactive UI trees. But it also hides the UI with display: none, which causes issues for gesture‑driven navigation. This article explores a workaround that keeps screens visible while still freezing effects across native and web.
• Building Apps Where AI Generates the UI by Mike Grabowski: Most AI apps wrap powerful models in a simple chat interface. This piece explores a different direction: letting the model generate the interface itself. Instead of returning text, it describes what the user should see next. The UI is decided at runtime, adapting to each user and context rather than being hardcoded in advance. The article walks through the architecture behind this pattern and shows it in practice with a project that turns static PDF forms into adaptive, AI-driven interviews.
• Sparkling: The Missing App Layer for Lynx.js? by Łukasz Chludziński: Lynx.js shipped with a strong brownfield story, but greenfield path felt incomplete. Sparkling changes that by bundling a CLI, native navigation, typed bridge APIs, and platform tooling into one cohesive layer. This article walks through bootstrapping a project, understanding the generated structure, and testing how navigation works in practice.
• Announcing: React Native Brownfield v3 with Expo Config Plugin by Artur Morys-Magiera & Hur Ali: 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.
• React Native Monorepo With pnpm Workspaces by Nazar Sydiaha: This guide shows how to configure pnpm workspaces for a React Native monorepo that spans mobile and web. It covers pnpm-workspace.yaml, pnpm.overrides, Metro configuration for hoisted deps, and a shared UI package used by both apps.

Videos, and talks

• Callstack x Vercel AI SDK Meetup The Safe Detonation Chamber: Building AI You Can Actually Ship by Szymon Chmal: How to design production AI systems using Vercel AI SDK, Workflows, and Sandbox , covering vendor lock‑in, long‑running workflows, and secure code execution.
• React Universe Meetup x Zalando LLM Inference On-Device in React Native: The Practical Aspects by Artur Morys-Magiera: React Universe Meetup x Zalando - A practical look at reliability, performance, libraries, and tradeoffs when running LLM inference locally in React Native apps.

Live streams

• React Native Evals: Making AI Code Quality Measurable recording & summary
• OpenClaw, Hermes Node and the State of AI Tooling recording & summary
• React Native 0.84: Hermes v1, WebAssembly, and Ecosystem Shifts recording

React Universe Summit 2026

React Universe Summit lands in New York City on June 23, 2026, bringing together 200+ CTOs, VPs, and Engineering Directors focused on how AI is reshaping React Native in production.

The day focuses on real delivery data, including velocity, cost, and team output, from teams already using AI across development, CI, testing, and OTA. Sessions cover brownfield adoption, AI’s impact on teams, modular architecture, enterprise infrastructure, and production case studies, with insights from engineers and leaders working at scale.

Book your spot now to join the conversation or reach out to us to discover Partnership Opportunities