React Universe Meetup, San Francisco

### React Universe Meetup, San Francisco

We’re teaming up with Expensify to bring you an event packed with tech talks and discussions. Plus, we’ve got some big news dropping from Callstack that you’ll definitely want to hear! Join us in person or online!

### Event details

📆 Date: Thursday, April 24, 2025
⏰ Time: 5:30 - 9:00 pm (PDT)
📍 Location: Expensify Office, 88 Kearny St 16th Floor, San Francisco, CA 94108, USA
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### ‍Agenda

5:30 PM – Doors open
6:00 PM – Introduction: Welcome to React Universe Meetup by Mike Grabowski, CTO & Founder at Callstack
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6:10 PM – User-Focused Performance Tracking by Tim Golen, Director of Engineering at Expensify

Performance metrics mean nothing if they don't reflect what users actually experience. In this talk, Tim will explore a pragmatic, user-first approach to performance tracking—one that cuts through vanity metrics and helps engineering teams focus on what really matters. You’ll see how defining the right KPIs with tools like StatsD and visualizing data in Grafana can uncover bottlenecks that impact real-world performance. We'll walk through how to identify low-hanging fruit and address the issues that make a measurable difference.

‍6:35 PM – Tips & tricks from The Ultimate Guide to React Native Optimization 2025 by Oskar Kwaśniewski, Senior React Native Developer at Callstack

Dig into some of the coolest React Native optimization techniques pulled straight from The Ultimate Guide to React Native Optimization 2025! We’ll show how to use React Native DevTools, take advantage of new React 19 hooks like use and useOptimistic, and apply view flattening to boost rendering performance and make debugging waaaay easier.

6:50 PM – Native Apps Without a Build Step by Michał Pierzchała, Principal Engineer at Callstack

If you’ve worked with React Native, you’re probably familiar with the complexity of Android and iOS build tools like Xcode, Gradle, Cocoapods, and CMake. The lengthy build times can also be a real chore. But with React Native, we’re mostly editing JavaScript files, so why do we need to rebuild our apps over and over again, either locally or on a CI server, which gets expensive quickly with macOS runners?
In this talk, I’ll show you the new React Native framework we’ve built for this use case (among others), which will allow you to skip the builds most of the time and reuse them across CI jobs for building, testing E2E, and dev environments.

7:15 PM – Q&A Session
7:30 PM - Networking time
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### How to join

🎟️ Please register to attend in person or access the exclusive livestream using the link below: https://www.callstack.com/events/react-universe-meetup-san-francisco