React Universe On Air

Many AI features in web apps send the user's audio, images, or text to a server and wait for the result. That adds network latency, moves data off the device, and ties the experience to a connection. Transformers.js gives developers another option: run the model in the browser.

In this episode, Mike Grabowski speaks with Nico Martin, Open Source ML Engineer at Hugging Face, about what browser AI can do today. They break down the Transformers.js pipeline API, ONNX Runtime, WebGPU acceleration, model downloads, browser caching, CPU fallbacks, and performance across devices.

Nico explains when local inference can beat a server round trip, why model size and hardware variation shape the user experience, and how browser code can handle parts of an agent workflow. He also shares early work on structured output and a custom WebGPU inference engine, where current experiments point to 5x to 10x speedups.

For developers deciding which AI tasks belong in the browser and which need the cloud, this episode maps the tradeoffs through speech recognition, background removal, embeddings, local tool calling, and on-device agents.

Check out episode resources on our website ➡️ https://clstk.com/4zMwzq9

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Chapters:

0:00 Welcome to React Universe On Air

1:04 Nico Martin's work at Hugging Face

2:04 What Transformers.js is

3:30 Browser AI beyond large language models

6:00 Bringing Python ideas into a JavaScript API

10:08 How the Transformers.js pipeline API works

14:23 Choosing compatible models and architectures

15:46 Why Transformers.js uses ONNX Runtime

19:01 CPU inference, WebGPU, and browser coverage

22:57 Model downloads, browser caching, and UX

28:28 Startup time and performance across devices

30:57 Why Transformers.js focuses on the browser

34:07 What developers misunderstand about browser AI

38:44 Building AI agents in the browser

43:19 Local fallbacks and hybrid AI

44:28 The browser AI roadmap

47:04 Hugging Face's custom WebGPU inference engine

50:57 Why speedups matter on constrained hardware

52:07 Nico's favorite browser AI use cases

VisionCamera v5 was five years in the making, and in this episode, Marc Rousavy joins Mike Grabowski to explain what changed, why v5 is more than a version bump, and how Nitro reshaped the foundation of one of the most widely used camera libraries in React Native.

They cover the bridge and JSI limitations that pushed VisionCamera toward a new architecture, the move to Nitro Modules, and the API decisions behind v5. The conversation also gets into the new constraints model, output objects, in-memory photo handling, barcode scanning, migration from v4, and the testing work needed to make camera features hold up across real devices.

If you build React Native camera apps, this episode is a detailed look at the engineering behind VisionCamera v5 and the decisions behind making complex camera features easier to ship and maintain.

Check out episode resources on our website: https://clstk.com/3Rj0dlN

Catch more React Universe On Air episodes: https://clstk.com/45ypLys

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Chapters:

0:00 Welcome to React Universe On Air

2:07 What VisionCamera is today

4:51 Barcode scanning and the new Data Scanner library

7:25 How VisionCamera helped shape Nitro

10:55 Frame processors, C++ glue, and the old JSI era

18:56 What is actually new in VisionCamera v5

21:45 The constraints API explained

30:12 Why third-party camera apps still struggle

33:29 The new output system and custom outputs

37:31 Imperative API, hooks, and components

39:01 Migrating from v4 to v5

43:25 AI, agents, and building VisionCamera v5

45:33 Testing, stability, and what comes next

48:25 Advice for teams building camera apps

50:50 Why web support is not on the roadmap

Some animations do not need a full animation engine. Sometimes you just want a view to fade in, translate, or move slowly without burning frame budget every time the UI thread gets busy.

Łukasz Chludziński talks with Janic Duplessis from App & Flow about React Native Ease, a small animation library built around platform-native primitives. They cover early React Native days, why Reanimated is still the right tool for complex interactions, and where a simpler React-like API can make sense.

Key takeaways:

- Why React Native Ease was created and what problem it solves

- How Core Animation can run animations outside the UI thread on iOS

- Why simple transitions do not always need Reanimated’s full flexibility

- Where Reanimated remains the right tool, especially for gestures and complex interactions

- How animation performance relates to frame budget, not just visible frame drops

- Why React Native’s maturity shifts more innovation into third-party libraries

- How focused open-source tools can push the whole ecosystem forward

Guest introduction:

Janic Duplessis is a developer at App & Flow and the creator of React Native Ease. He has been working with React Native since the early iOS-only days and has contributed to React Native Core, including work around animation internals and native-driver concepts.

Check out episode resources on our website 📚

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Rudrank Riyam joins React Universe On Air to talk about App Store Connect CLI, an open-source tool for automating App Store Connect workflows without living in the dashboard.

What started as a way to pull TestFlight feedback turned into a broader interface for metadata, submissions, localization, analytics, reviews, and release operations. Mike Grabowski and Rudrank discuss why these workflows are a strong fit for CLI automation, why Go became the right language for an agent-built tool, how teams are using it in CI/CD and agent workflows, and what changes when multiple coding agents build against the same codebase.

They also get into code structure, command design, agents.md, public vs. private App Store Connect endpoints, and what changed after Rork acquired the project while keeping it open source.

What we cover:

- Why App Store Connect workflows are a good fit for CLI automation

- How the tool handles TestFlight feedback, metadata, localization, analytics, reviews, and submissions

- Why Rudrank chose Go over Swift for an agent-built CLI

- What he learned from running multiple agents against one open-source project

- How clear structure and command naming make a codebase easier for both humans and agents

- What Rork’s acquisition means for the project going forward

Guest: Rudrank Riyam is a software engineer at Rork and the creator of App Store Connect CLI. He works at the intersection of Apple development, release tooling, and agentic workflows.

Zack Ebenfeld joins Michał Pierzchała to talk about AI-assisted coding, testing, QA, code review, and why verification matters more than ever in mobile workflows. It is a practical conversation about trust, feedback loops, and how engineering work is shifting from pure implementation toward judgment, architecture, and product thinking.

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