🎉 @margelo_com Joins Callstack to Advance High-Performance React Native Engineering Vienna, Austria. 1 September 2026. Callstack, a leader in React Native and cross-platform development, today announced that Margelo, the Vienna-based high-end engineering company behind Nitro Modules, VisionCamera and react-native-mmkv, is joining Callstack in a transaction valuing Margelo at more than EUR 20 million. Margelo builds high-performance technology for React Native. Nitro Modules (34M downloads) lets developers write fast, type-safe native modules in C++, Swift or Kotlin, and quickly gained widespread traction across the ecosystem. VisionCamera (40M downloads), Margelo's enterprise-grade open-source Camera framework and react-native-mmkv (67M downloads), a key-value storage library, power countless React Native apps today. Callstack has spent a decade helping large organizations adopt, scale and operate React Native, contributing to the framework and its open-source ecosystem along the way. Together, the two teams give clients the strongest React Native performance expertise in the market, backed by delivery proven in complex enterprise environments. Margelo's technology and Callstack's delivery experience will now be available to the same clients. The timing reflects a fundamental change in how software is built. AI is making implementation faster and cheaper, but architecture, performance, native integration, validation and release safety are becoming more important, not less. These are the fundamentals on which both companies have built their reputations and on which they will continue to build together. "Margelo has built some of the strongest performance technology in React Native. Callstack has spent a decade helping large organizations adopt and scale the framework. Bringing those strengths together gives us the team and reach to solve more of the hard problems that determine whether software succeeds in production," said Mike Grabowski, CEO and Founder of Callstack. "At Margelo, we’ve built high-performance technology that developers already rely on. We’re excited to partner with Callstack to bring it to more clients and scale its impact. As software development becomes increasingly agentic, we want that technology to provide the foundation teams need to build reliable software with agents," said Marc Rousavy, CEO and Founder of Margelo. Margelo's existing open-source libraries will remain open source. Marc will continue to lead their development and help shape the combined company's offering. The transaction follows Callstack's 2025 growth investment and supports its strategy to expand technology and open-source capabilities while growing internationally.

Join Callstack, @jetbrains & @expo for From Design to Shipped: A Modern App Development Meetup on October 22, 2026 at the JetBrains Amsterdam office. You’ll here from: 🔹 Michał Pierzchała (@thymikee): “From Design to Done in One Shot With a Cheap Model” 🔹 Craig Walker & Kasper Peulen (@KasperPeulen): “Agents Didn't Kill the UI Developer Workflow - They Changed It” 🔹 Cedric van Putten (@cedric_dev) from Expo Doors open at 5:45 PM CEST. Free entry, pizza & drinks after the talks. Sign up now: luma.com/i8wkxgyg

New tool for token-efficient performance profiling React just dropped 👇

Meta just announced new ways to build for Meta VR devices, and React Native is part of that story. The new Meta VR Layout SDK brings spatial, multi-panel experiences to React Native, while the new Expo Launch integration makes the path from an Expo project to Meta's Release Channels and Store much simpler. We've been working with @Meta on React Native support for VR, and today we're updating our developer documentation alongside the announcements. More coming soon in our React Native reference app as we add examples for the new spatial APIs. Read more 👉 clstk.com/3VvaKMc

Last week, our colleagues Andoni Santamaria and Felipe Ugena attended @AgentConf in Warsaw. 🔹 Specialized models 🔹 Multi-agent coordination 🔹 Observability 🔹 Production-ready agentic systems and more! @callstackio plainconcepts.com/agent-conf…

Had a chance to play around with Apex on @AgentConf last week. It’s incredible. It’s absolutely incredible. GJ @callstackio team!

big announcements next week, follow this account ↓

Can't believe Opus 5.5, GPT-6 Sol, GPT-6 Luna, and I all launched today.

hello, world!

Teams can share plenty of code and still run iOS and Android as separate products. Where does new mobile work land by default, and who owns the native exceptions? React Native at Scale 2026 looks at how experienced teams make that call 👉 clstk.com/4hpke31