On April 24, 2025, we brought the React Universe Meetup to San Francisco, this time hosted at Expensify HQ. Part of our ongoing community series, this meetup connected React and React Native professionals for an evening of sharp insights, real-world challenges, and meaningful conversations about where the ecosystem is heading.

We kicked off the event with a welcome from Mike Grabowski, Callstack’s CTO and co-founder, who set the stage for the night with a look at the React Universe and how we’re creating space for open conversations around cross-platform development.

Tim Golen, Director of Engineering at Expensify, opened the speaker lineup with a talk on User-Focused Performance Tracking. Tim challenged the traditional use of performance metrics, making a case for tracking what actually matters to users. He shared how his team defines meaningful KPIs, uses StatsD to measure them, and visualizes performance data in Grafana. The takeaway? Stop chasing vanity metrics, focus on what impacts the real user experience.

Next up, Oskar Kwaśniewski, Senior React Native Developer at Callstack, delivered a talk packed with practical insights from The Ultimate Guide to React Native Optimization 2025. He shared battle-tested techniques like view flattening, performance boosts using React 19’s new hooks (^use, ^{useOptimistic}), and tricks to make React Native DevTools your debugging best friend. If you're building with React Native today, this talk was a goldmine.

To close out the talks, Michał Pierzchała, Principal Engineer at Callstack, took the stage with Native Apps Without a Build Step. He tackled one of the biggest pain points in React Native dev: long and expensive build cycles. Michał introduced a new framework built by the Callstack team that lets you skip most builds entirely, saving time and CI costs by reusing builds across dev, testing, and deployment environments. Game-changer.

Couldn’t make it? No worries, recordings from the stream will be available soon, and we’ll be releasing individual talks shortly after.