100+ Enterprise Clients

7B+ active clients users

$1.8T Clients Revenue

From startups to Fortune 500.

From React Native migrations to AI-native delivery infrastructure, these are the products, platforms, and engineering systems we helped teams move forward.

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Tooling Setup
AI-Driven QA & Testing
Software Development
React
React Native
Web

Engineering AI Loops for a Cross-Platform Design System

We helped an enterprise software team, with an initial rollout spanning 30+ engineers, turn Figma designs into production-ready code faster, with more consistent UI and built-in quality checks across web and mobile.

60+

components mapped with full Code Connect coverage

~6x

faster prototyping for a typical enterprise screen

<2%

visual diff threshold for generated screens

1

install sets up AI workflow for Claude Code & Cursor

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End-to-End Product Development
Self-Hosted CI/CD Infrastructure
Sports & Entertainment
Android
iOS

Accelerating Teamworks' Mobile Delivery With Re.Pack and Module Federation

10

min from code change to mini-app release

multi-daily

staging deployments instead of weekly releases

7

mini-apps supported in one modular mobile platform

2

CI/CD lanes for mini-app and host-app distribution

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AI-Assisted Migrations
End-to-End Product Development
Self-Hosted CI/CD Infrastructure
Automotive
iOS
Android

Migrating iOS and Android Apps to React Native for AutoZone

2x

growth in mobile user base during the migration period

4.2 -> 4.7

app rating increase after migrating to React Native

0

missed releases during the transition to React Native

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Architecture & Performance
Feature Development
Software Development
iOS
Android

Creating React Native SDK Wrapper for Rive

100k

weekly downloads on npm

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End-to-End Product Development
Feature Development
Software Development
iOS
Android

Launching White-Label Super App for Zephyr Cloud With Re.Pack

We integrated ZephyrCloud with React Native and developed a white-label application to showcase Zephyr features as well as provide easy getting started story.

Short heading goes here

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Architecture & Performance
AI-Driven QA & Testing
Self-Hosted CI/CD Infrastructure
Finance
Android
iOS

Enhancing Application's Performance for Expensify

Discover how we revamped the Expensify app for lightning-fast experiences, guided by a systematic DMAIC approach.

5x

faster message sending time

4.5x

faster search screen loading time

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Self-Hosted CI/CD Infrastructure
Architecture & Performance
Finance
iOS
Android

Building Scalable Observability for a High-Growth React Native App

3→1

analytics systems unified into a single interface

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End-to-End Product Development
Self-Hosted CI/CD Infrastructure
Architecture & Performance
Media & Streaming
TV
Tizen

Launching a High-Performance React Native App on Samsung TV

5

platforms under one RN codebase: tvOS, FireTV, Tizen, LG, Vizio

28.6%

lower TTI compared to the inherited RN app (15.27s → 10.9s)

0

extra hires needed to support new platform

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Architecture & Performance
End-to-End Product Development
Media & Streaming
TV

Optimizing Android TV Startup for Global Streaming Platform

5%

faster startup time on FireTV and FireHD devices

1 line

to improve startup performance

0 rewrites

required, change applied at build level

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Feature Development
End-to-End Product Development
Software Development
Web
iOS

Building a browser-based React Native playground for Expo

We partnered with Expo to enable instant prototyping, real-device preview, and easy sharing of React Native projects, all without local setup.

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Architecture & Performance
End-to-End Product Development
Sports & Entertainment
iOS
Android

Improving Chat Performance and Creating a Custom UI Library for Dream11

We enhanced the performance of the Dream11 platform by optimizing chat functionality for low- and medium-end devices, and creating a custom UI component library.

78%

bundle size reduction (from 50 MB to 11 MB)

30%

faster component mount time after render optimization

60%

faster initial load time enabled by switching to Hermes

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Team Training
AI-Assisted Migrations
Architecture & Performance
Retail & E-commerce
Android
iOS

Training HelloFresh Engineers to Build Production Apps With React Native

2.8x

increase in knowledge over 8 weeks (25% → 71% assessment scores)

15

developers trained across web and native backgrounds

86%

of devs self-rated their knowledge as 3/5 or higher after training (up from 0%)

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End-to-End Product Development
Feature Development
Team Training
Finance
iOS
Android

Enhancing Performance of Momo's Super App With Re.Pack

MoMo successfully migrated its platform and mini apps to a new architecture using Re.Pack, boosting performance and scalability.

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AI-Assisted Migrations
Self-Hosted CI/CD Infrastructure
Retail & E-commerce
Android
iOS

Migrating a Legacy React Native App to Expo for Faster Builds and Simplified Releases

6x

faster builds after replacing Jenkins with EAS

1.5x

more reliable builds with EAS

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Architecture & Performance
AI-Assisted Migrations
AI-Driven QA & Testing
Finance
Android
iOS

Migrating Questrade Edge Mobile to a Faster, More Scalable Architecture

33%

fewer re-renders across most features

18%

faster time-to-interactive

-28%

CPU usage in critical trading flows

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End-to-End Product Development
Feature Development
Software Development
iOS
Android

React Universe App: Networking Evolved With Liquid Glass

63%

adoption rate; majority of attendees registered in the app

67%

of attendees connected through QR badge sharing

45%

created personalized badges to showcase identity and goals

49%

of attendees onboarded before day one, arriving ready to network

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Feature Development
Architecture & Performance
Automotive
Web

Migrating AutoZone’s Storefront to Next.js for Better Performance and SEO

#1

SEO rank, recovering from 3-9

260kB

less in blocking JS payload

2–5x

faster feedback loop

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AI-Assisted Migrations
Feature Development
End-to-End Product Development
Healthcare
iOS
Android

Modernizing 7Cup's React Native Codebase and Adding Platform Features

130%

increase in users post-upgrade

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From strategy to infrastructure

Everything you need to ship at AI speed

You understand how we work. Now pick the lane.

Everything you need to ship

Engineering

One partner for all platforms
Complex migrations in months
Deep native engineering work

Make delivery faster. Keep releases smoother.

Infrastructure

Review AI-written code faster
Own your delivery infrastructure
Open source at the core

From AI tools to AI teams.

Adoption

Setup the right AI tools
Measure the real ROI
Upskill the entire team

Adopt AI safely without loosing speed

Governance

Private and on-device models
Pass compliance reviews
Control data exposure

Every engagement starts with one conversation. Let's map your situation to the right model.

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Clients

Trusted by enterprise teams at scale

I appreciate their attention to detail, flexible approach and a high degree of expertise.

Glen Moriarty

Founder and CEO

Their engineers proved to be a crucial part of our mobile app relaunch project.

Brian Aznar

Engineering Director

We had been struggling with React Native application performance until we met Callstack.

Huỳnh Chí Hùng

Associate Director

The trainers are always very helpful and supportive. It really makes a difference!

Artem Musiienko

Staff Eng

I recommend them as a trusted tech partner for running complex projects.

Jin Chung

Co-Founder, CTO

Not only does Callstack have tremendously talented engineers, but I know they care about the success of the project as much as I do.

TC Davis

Product

Teamworks needed Module Federation, we helped make it real

Michael Song

Head of Platform

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