Callstack

Have you marked April 27 in your calendar for our webinar with Zattoo? We’ll focus on how they reduced coordination overhead and improved delivery speed by moving away from separate TV codebases and adopting a shared React Native approach. Join us to hear how this worked in practice, what changed in their team setup, and how it affected day-to-day work. Pavel Verkhovskyi 🇺🇦 (Director of Engineering at Zattoo) and Bogdan Plieshka (Principal Frontend Engineer at Zattoo) will share their experience, hosted by Ada Gawrysiak and Łukasz Chludziński. 📅 April 27, 5 PM. Save your spot ➡️ https://clstk.com/3Qid1Id

KLJS x React Universe Meetup, Kuala Lumpur is happening on May 5th at 7:30 PM. This session is built around real production work with React Native. Thim Yun Lee, Senior Engineer at Ryt Bank, will speak about building and running a digital bank on React Native and Hur Ali, Callstack’s Engineer, will join on stage with the talk about migrating native apps with AI-assisted workflows. This meetup will be focused on how React Native holds up in production, with concrete examples and tradeoffs from teams shipping real apps. We will announce the third speaker soon. Save your seat now 👉 https://clstk.com/4cxsiME 

Even small edits to a SKILL.md can change how an agent behaves in the most unexpected way. It might still “work” when you test it locally, but fail on a different runner, pick the wrong tool, or take a longer path than expected. Skillgym runs real sessions across runners and lets you assert what “correct” means, so you can catch regressions before users do. Learn more 👇 https://clstk.com/4mKDSJa

TV platforms are converging, and teams are under increasing pressure to deliver consistent experiences across multiple environments without multiplying effort. This session shares how Zattoo approached that challenge by moving from separate native applications to a unified React Native strategy, focusing on speed of delivery, maintainability, and long-term scalability. We’ll walk through the key decisions behind the migration, how it impacted team structure and day-to-day work, and what the transition process looked like in practice. You’ll hear what worked well, what didn’t, and the main challenges encountered along the way, including performance considerations and platform differences. The session also covers how many platforms Zattoo is targeting today and how their approach enables them to expand further without starting over. It’s a practical look at building high-quality TV apps with a shared foundation, based on real production experience. Join us to learn from Zattoo’s experience and see how a shared React Native approach can support your TV platform strategy.

Callstack is heading to AI Engineer: Miami and React Miami next week for some sun and serious AI talk 🦩 🌊 💻 📲 Alongside the talks, we’re hosting a small CTO Brunch on April 22nd. It’s focused on agentic development and what it means for React Native teams working in production. Rsvp: https://luma.com/qm4y4ezc If you can’t make the brunch and would still love to chat, we’re also opening 1:1 technical sessions with our engineers during the week. #ReactMiami #AIEngineer #ReactNative #MiamiTech #AIEngineering

Fresh React Native Evals run is live. A few concrete updates: - we added Lists and React Native APIs - Claude Opus 4.7 scored below Claude Opus 4.6 in this run We're re-running Opus 4.6 on the current API to check whether this is a real delta or degraded performance over time. One early takeaway: Composer is scoring very high on the current suite. That said, we're already expanding the benchmark with harder evals and additional project coverage, so we expect the picture to evolve as the benchmark gets tougher. We've also made automation improvements to the release flow, which should make updates faster and smoother from here. Check the results yourself (link in the comments) ⬇️

Keith Kurak, Developer Success Engineering Manager at Expo, joins React Universe Summit as our next confirmed speaker. He works closely with teams building and scaling apps with React Native, focusing on what developers need to ship and grow. His perspective comes from supporting real-world apps and the people behind them. As the React Native ecosystem continues to evolve, understanding how to build, scale, and support production apps is becoming central. Join us on June 23, 2026 at React Universe Summit. Be in the room. Get ticket ➡️ reactuniverse.com

A quick reminder 👇 We’re heading to Miami next week for AI Engineer Miami and React Miami. Alongside the talks, we’re hosting a small CTO Brunch on April 22nd. It’s focused on agentic development and what it means for React Native teams working in production. If you can’t make the brunch and would still love to chat, we’re also opening 1:1 technical sessions with our engineers during the week. Contact Katarzyna Mirońska- Veigas to book your spot 📅

Who's heading to Miami next week? I'll be there all week, starting at AI Engineer and then heading to React Miami, where I'll be talking about Voltra. If you want to connect on-site, chat about what I'm building, or get a sneak peek at what's coming next, let me know 😀