Local-First, Voice AI, and App Security with Kraen Hansen & Ola Desmurs-Linczewska

What happens when you combine voice agents and teddy bears? A hands-on look at local-first systems, voice AI, and security lessons from poking real apps. Kraen Hansen and Ola Desmurs-Linczewska talk about Software, AI Agents, parenting, stoicism and more!

Vercel’s v0 iOS app is built with React Native, but it looks and feels like a fully native iOS product. In this episode of React Universe On Air, we go deep into how the v0 mobile app was built: from choosing Expo and going iOS-first, to writing native modules, fixing low-level React Native issues, and upstreaming improvements back to the ecosystem. This is a hands-on engineering conversation with Fernando Rojo, Szymon Rybczak, and Oskar kwaśniewski about real trade-offs, real constraints, and what it takes to ship a polished app under real deadlines. Chapters 00:00 Welcome to the React Universe 00:50 Meet our guests 02:42 v0 app overview 03:45 Iterating to greatness 05:07 Choosing Expo and initial tech decisions 07:55 Code sharing with v0 website 11:03 Open Source contributions 13:20 React Native Core fixes 15:40 Android version? 18:42 Modal issues we fixed 23:20 Working with React Native Core 26:16 Balancing deadlines and root cause analysis 27:23 Native Modules and custom solutions 29:16 Minimalistic UI challenges 30:44 Floating Composer concept 33:41 Feature flags and testing 36:48 WebView swiping and custom forks 45:16 Launch experience and security concerns 50:17 Final thoughts

This year, React Universe On Air is doing something different for Christmas. No guests, demos, or framework updates. Instead, Ola Desmurs Linczewska tells a Christmas story. A (Secure) Christmas Carol is a holiday fairytale for JavaScript and React Native developers. Set on Christmas Eve, it follows Npmezer Scrooge, a senior engineer who believes deadlines matter more than holidays, and warnings can always wait. Over the course of one long winter night, he’s visited by unexpected guides who show him what his choices look like across time: the optimism of the past, the quiet damage of the present, and a future no one wants. All technical details, real-world security issues, and references mentioned in the story are explained in the show notes 📚  https://clstk.com/4pEVYwv We’ll be back in January with regular episodes. Until then, stay kind, stay curious, and have yourself a very merry Christmas.

It’s a practical, developer‑focused look at the early days of React Native on VR: what works today, what’s different from mobile, and why so many app ideas translate better than you might expect. Chapters: 00:00 Introduction to React Native on Meta Quest 01:10 Meet the guests: Jan Jaworski and Ram N 01:28 Ram’s background and experience 04:10 Jan’s background and experience 06:09 Exploring React Native on Meta Quest 07:09 How Meta Quest started 11:00 Getting started with React Native on Meta Quest 14:30 Betting on AOSP 17:00 First-mover advantage and developer opportunities 21:32 Differences between mobile and VR 24:45 Running Expo projects on the headset 25:28 React Native on Meta Quest, now for real 27:27 Starting a React Native project on Meta Quest 28:49 Developing and debugging on Meta Quest 30:19 Do you need a headset or an emulator? 31:57 Virtual Reality Development Experience 38:09 AI tooling 40:02 Meta Horizon Start Developer Competition 45:02 Conclusion and final thoughts

The NFL runs on tight deadlines. Every kickoff and Super Bowl demands that millions of fans get flawless live video, stats, and fantasy features, whether they’re on iPhones, Xboxes, or connected TVs. In this episode of React Universe On Air, Mike Grabowski talks with Michael Blanchard (Director of Engineering at the NFL), about how React Native became the backbone of this high-pressure, multi-platform ecosystem. Michael shares his journey from web engineer to leading NFL’s engineering teams across nfl.com, three mobile apps, a cross-platform video player, and a suite of connected TV apps. Together with Mike, he explores the NFL’s migration strategy, the transition from Haul/Webpack to Metro and Expo, and the cultural shifts that helped merge web and native engineers into one collaborative team. You’ll learn: ➡️ Why the NFL went full Greenfield (twice) ➡️ How NFL+ shaped their second rewrite ➡️ Lessons from moving from Haul/Webpack to Metro ➡️ How Expo SDKs gradually replaced community libraries ➡️ How GitHub Actions + EAS Build reshaped their CI/CD pipeline ➡️ Strategies for handling 20–30 PRs daily in a monorepo ➡️ How React Native powers mobile, web, and multiple connected TVs ➡️ What cultural shifts enabled true cross-platform collaboration Catch more React Universe On Air episodes 🎧 https://clstk.com/4gp8Cw5 Sign up for our newsletter ✉️ https://clstk.com/4mfmRof Follow us on X 🐦 https://x.com/callstackio Chapters: 00:00 Welcome to the React Universe 01:35 Meet Michael Blanchard from NFL 03:03 NFL's digital presence and platforms 04:24 React Native in NFL's mobile apps 08:32 How React spread across all platforms 11:47 Collaboration between web and native teams 18:11 Technical decisions regarding different platforms 23:48 V2 of NFL's flagship app 25:14 Choosing migration strategy 30:10 Maintaining more product versions 34:33 Adopting Expo 42:10 Modernizing CI/CD 46:48 Team structure and workflow at NFL 53:29 Final thoughts

What really happens when React Native’s core contributors gather behind closed doors? In this episode of React Universe On Air, recorded live at React Universe Conf 2025, host Łukasz Chludziński sits down with Joel Arvidsson, Jay Meistrich, and Thibault Malbranche to unpack the hottest debates and wisest insights from the Core Contributor Summit. They dive into: ➡️ How the cooperation between consultancies, big organizations like Meta or Microsoft, and OSS contributors looks like ➡️ 2025 as the “year of stability” for React Native ➡️ The promise (and pain) of React Native for desktop apps ➡️ Flipper’s decline and new community-driven DevTools ➡️ Whether React Native 1.0 is just a marketing label or a true milestone ➡️ How agencies and individuals balance open source with client work ➡️ Practical advice for engineers who want to contribute and join the conversation Chapters: 00:00 Welcome to the React Universe 01:21 Meet our guests: Thibault Malbranche, Joel Arvidsson, Jay Meistrich 02:33 What is Core Contributor Summit 04:02 Meta vs. community usage of React Native 07:19 Year of stability & tooling challenges 09:00 Surprise session: React Native for Desktop 16:10 Concrete outcomes vs. planting seeds 21:02 Open Source dynamics & collaboration 27:30 React Native 1.0 33:45 Future directions & getting involved 36:50 Final thoughts Catch more React Universe On Air episodes 🎧 https://clstk.com/423vF9D Sign up for our newsletter ✉️ https://clstk.com/3Kb23kM Follow us on X 🐦 https://x.com/callstackio

Many React Native apps ship without full observability. The result? Blind spots in performance, crashes, and user behavior once your app is in the wild. In this episode of React Universe On Air, Łukasz Chludziński sits down with Jonathan Munz (Senior Software Engineer at Embrace) and Adam Horodyski (React Native Expert at Callstack) to unpack how OpenTelemetry can bring structure and clarity to mobile monitoring. They break down why mobile observability is harder than observability on backend, what the OTLP protocol enables, and how to instrument React Native apps without locking into a single vendor. You’ll also hear how community-driven tooling like React Native OpenTelemetry and the Embrace React Native SDK can simplify setup and improve data portability. You’ll learn: ➡️ How observability and OpenTelemetry work together ➡️ The 3 core OpenTelemetry signal types for mobile ➡️ Why mobile instrumentation is more complex than backend telemetry ➡️ How OTLP improves interoperability between tools ➡️ Where auto-instrumentation is still missing in React Native ➡️ The role of Embrace and open-source libraries in reducing setup overhead Check out episode resources on our website 📚 https://clstk.com/4104nAF Catch more React Universe On Air episodes 🎧 https://clstk.com/45EWnYe Monitor what matters in your React Native app with Callstack’s help 🤝 https://clstk.com/3HoM3KI Sign up for our newsletter ✉️ https://www.callstack.com/newsletter Follow us on X 🐦 https://x.com/callstackio Chapters 00:00 Welcome to the React Universe 01:07 Meet our guests 03:07 Defining observability and OpenTelemetry 04:32 Signals in observability 11:57 Challenges with observability in React & React Native 16:04 Standardization and OpenTelemetry protocol 18:08 Embrace and Open Telemetry 21:29 Future of OpenTelemetry in mobile 27:23 Exploring React Native OpenTelemetry 29:54 Community involvement in OpenTelemetry 37:34 Real observability in React Native 46:41 Future of React Native observability 50:40 Hey, listeners, here’s what we want you to do 54:46 Conclusion and final thoughts

Should you be afraid of monorepos? Not with Nx. Tune in and learn how to scale apps without scaling pain. In this episode of React Universe On Air, Łukasz Chludziński chats with Jordan Powell from Nx to explore what it really takes to build and manage a monorepo at scale. From dependency graphs to distributed CI tasks, they break down how Nx helps teams stay fast, focused, and frustration-free. Whether you're just getting started with Yarn Workspaces or running into CI bottlenecks, this episode gives you the strategies and context to go further with less overhead. Key learnings ➡️ The difference between monorepos and monoliths ➡️ How Nx graphs improve selective builds and testing ➡️ What “ownership rules” mean for large codebases ➡️ How distributed task execution saves time in CI ➡️ Why better DX equals better business outcomes ➡️ Real-world patterns for React Native and full-stack monorepos Catch more React Universe On Air episodes 🎧 https://clstk.com/44Bj51X Get your React Universe Conf 2025 tickets 🎟 https://clstk.com/4nFqTZ1 Sign up for our newsletter ✉️ https://clstk.com/3TrnIGH Follow us on X 🐦 https://x.com/callstacki 00:00 Welcome to the React Universe 00:42 Meet Jordan Powell from Nx 02:42 The joy and pain of testing 04:03 Understanding monorepos 06:52 The origins of Nx 09:41 Developer experience and its business impact 12:10 Nx vs. other tooling and a closer look at its features 21:07 Getting started with Nx 25:27 Collaborating on projects 28:00 Assigning ownership and scoping projects 29:30 Managing dependencies in a monorepo 31:16 Handling multiple framework versions and migrations 32:40 Real-world examples of large-scale monorepos 36:10 Distributed task execution with Nx Cloud 39:08 Efficient testing in a monorepo 42:55 The Future of Nx with AI integration 47:27 Conclusion and final thoughts

What if you could skip most native builds—and still ship confidently? In this episode of React Universe On Air, we explore how the React Native Enterprise Framework (RNEF) helps large teams dramatically reduce build times and streamline development at scale. Our guest Michał Pierzchała, Principal Engineer at Callstack, shares how RNEF was built to solve real-world bottlenecks in enterprise React Native projects. Alongside him, Łukasz Chludziński discusses his experience testing the framework in a live production environment, where build times dropped from 35 minutes to just 3. What you'll learn: - How RNEF slashes native build times with CI-based caching - Ways to adopt the framework incrementally—no full rewrite required - How brownfield support lets you drop React Native into native apps easily - What makes RNEF different from Expo and Community CLI - Real-world savings and improved developer-QA workflows Check out episode resources on our website 📚 https://clstk.com/4e5OL3W Explore React Native Enterprise Framework ✨ https://clstk.com/4kAt7ap Catch more React Universe On Air episodes 🎧 https://clstk.com/3SJRk1G Get 20x faster builds on your CI in less than a week with our help 👉 https://clstk.com/3ZWJ9Tq Sign up for our New York meetup in June 2025 👉 https://clstk.com/4kEyG7C Follow us on X 🐦 https://x.com/callstackio 00:00 Welcome to the React Universe 01:07 Host & guest introductions 02:40 Project overview: React Native Enterprise Framework 04:04 Challenges in large repositories 04:50 Testing and build time optimization 07:31 Building RNEF on a real-life use case 12:37 Integrating RNEF POC to the project 15:00 Incremental adoption mindset 21:42 What it all has to do with React Native Community CLI 26:05 Optimizing build process with smart caching 44:06 Seamless collaboration between devs & QA 47:28 Brownfield projects with RNEF 55:50 Where RNEF stands in the ecosystem 59:08 What does it mean to be a React Native framework?

Is rewriting your native app really the only way to go cross-platform? In this Coffee Talk episode, we explore how React Native Brownfield offers a smarter path forward. Łukasz Chludziński invites Oskar Kwaśniewski and Burak Güner—who work directly on React Native Core and brownfield tooling—to discuss how recent advances in React Native have made brownfield integration far more viable, stable, and scalable. You’ll learn: ➡️ Why brownfield isn’t what it used to be (goodbye, brittle bridging) ➡️ How `RootViewFactory` and `ReactNativeFactory` APIs simplify setup ➡️ What’s new in React Native Brownfield 1.0.0 ➡️ How to keep your architecture clean while integrating React Native ➡️ What this means for modern native stacks like SwiftUI, Jetpack Compose—and future-facing platforms like visionOS Whether you’re maintaining a legacy app or building for what's next, this episode gives you a blueprint for hybrid success. Explore React Native Brownfield 🙌 https://github.com/callstack/react-native-brownfield Check out episode resources on our website 📚 https://bit.ly/3ESW3Lf Catch more React Universe On Air episodes 🎧 https://bit.ly/44A0q8q Get your React Universe Conf 2025 tickets 🎟 https://hubs.li/Q03l-47N0 Sign up for our newsletter ✉️ https://bit.ly/3H2xsE6 Follow us on X 🐦 https://x.com/callstackio Timestamps 00:00 Welcome to the React Universe 02:00 Meet our guests: Oskar & Burak 02:50 Let’s talk brownfield app development 03:37 Craziest brownfield setups our guests have seen 08:19 Greenfield vs. brownfield React Native 14:14 How we used to approach brownfield development 18:20 Callstack’s React Native Brownfield 23:30 RootView Factory & React Native Factory 28:50 New Features in React Native Brownfield 1.0 35:35 Sharing data between native and JavaScript 41:00 How about using different React Native versions 43:30 Cost of complexity 47:00 Learn more and get in touch with our guests