React Native Paper
Material Design for React Native (Android & iOS)
Expensify uses agent-device. Mobile bug evidence and profiling are part of its documented usage story.
What you get
iOS and Android from one codebase, ready for web, desktop, or TV when you are. Expensify ships 5x faster on shared React Native code.
Camera, gestures, push, payments, biometrics, Live Activities, App Clips. We wire up the platform features your product actually uses.
Modular structure, typed interfaces, shared UI systems. Built so your team scales development without the architecture fighting back.
Agents scaffold, refactor, and test in parallel under senior review, so work keeps moving between sessions. You get more shipped per sprint without lowering the engineering bar.
Your app feels fast on low-end Android and the latest iPhone, because we optimize for both, not just the demo device.
Well-documented code, clear ownership, handoff-ready onboarding. Your in-house team continues without guesswork.
Security, reliability, and accessibility standards from day one, proven across 100+ enterprise projects and React Native apps serving billions of users.
How we work together
Our senior engineers join your team to ship features, guide technical decisions, and strengthen delivery.
We take agreed work from technical planning to release, with clear responsibilities and progress you can see.
We address a performance, migration, or infrastructure challenge, or run training around your team’s needs.
Case studies




Mobile App Development
We deliver cross-platform apps that meet your performance, UX, and quality bar, at any stage. Let's scope the build.
We had been struggling with React Native application performance until we met Callstack.

We’ll connect you with the right expert within 24 hours.
Still have questions?
Yes. We can lead end-to-end delivery or embed alongside your product and design teams.
We use shared UI systems and optimize for both low-end Android and the latest iPhone, so your app feels fast and native on every device, not just the demo one.
Yes. From one codebase, we audit for platform gaps and implement missing functionality to maintain parity across releases.
We track evolving guidelines and make sure your app meets review criteria to avoid unnecessary delays.
We define clear ownership, integrate with your release planning, and support parallel development tracks.
We offer both. You own everything we build, with well-documented code and handoff-ready onboarding, and our teams can keep supporting maintenance and platform evolution post-launch.
Absolutely. We adapt the UI and features to feel native on new form factors while reusing core logic wherever possible, and the same codebase is ready for web, desktop, or TV when you are.
Agents scaffold, refactor, and test in parallel under senior review, so work keeps moving between sessions. You get more shipped per sprint without lowering the engineering bar.