--- title: "Expert Engineering & Agentic Delivery Services | Callstack" description: "Build and scale React and React Native products with expert engineers, or improve software delivery with custom agents, AI workflows, and testing." url: https://www.callstack.com/services updated: 2026-10-30T10:16:49.049Z --- # Expert Engineering & Agentic Delivery Services | Callstack Build and scale React and React Native products with expert engineers, or improve software delivery with custom agents, AI workflows, and testing. React Foundation · used by 50M+ developers · 100+ Enterprise Clients ## Big plans need the right partner. More platforms. Bigger ambitions. A roadmap that won’t wait. Get the React and React Native expertise to make the right technical calls, with agents and workflows that turn more of your plans into shipped products. Trusted by 100+ enterprise clients Expensify · Ticketmaster · DirecTV · MLS · PWC · Evernote · AutoZone · MoMo · Dream11 · Rainbow · Futurewei · RIMAC · Hello Fresh · Haaretz · ForaTravel · CelcomDigi · Teamworks · Boats · Questrade · Dialogue Expert engineering ### Build and scale React Native apps. - [Feature Development](https://www.callstack.com/capabilities/feature-development) - [End-to-End Product Development](https://www.callstack.com/capabilities/end-to-end-product-development) - [Architecture & Performance](https://www.callstack.com/capabilities/architecture-performance) - [Enterprise Infrastructure](https://www.callstack.com/capabilities/self-hosted-ci-cd-infrastructure) - [Team Training](https://www.callstack.com/capabilities/team-training) - [Migrations & Upgrades](https://www.callstack.com/capabilities/ai-assisted-migrations) - [Find out more about Expert Engineering](https://www.callstack.com/ai-native-engineering) Agentic Delivery ### Turn AI into better software delivery. - [AI SDLC Advisory](https://www.callstack.com/capabilities/ai-sdlc-advisory) - [AI-Driven QA & Testing](https://www.callstack.com/capabilities/ai-driven-qa-testing) - [Custom Agents](https://www.callstack.com/capabilities/custom-agents) - [Custom & Private Models](https://www.callstack.com/capabilities/custom-private-models) - [Find out more about Agentic Delivery](https://www.callstack.com/agentic-delivery) - React Foundation Founding Member · 300+ commits to React Native · Contributing since 2016 - 100+ Enterprise projects delivered - Industry runs on our tooling · 50M+ OSS downloads / month - [3.7× Lower task cost vs Opus 5.5](https://apex.callstack.com) - “I recommend them as a trusted tech partner for running complex projects.” — Jin Chung, Co-Founder, CTO / Rainbow · “Their engineers proved to be a crucial part of our mobile app relaunch project.” — Brian Aznar, Engineering Director / Major League Soccer · “I appreciate their attention to detail, flexible approach and a high degree of expertise.” — Glen Moriarty, Founder and CEO / 7 Cups · “The team at Callstack are the most experienced engineers in the React Native community.” — Nader Dabit, Senior Developer Advocate / AWS · “Their ability to deliver, and follow through, is unparalleled in the React Native ecosystem.” — Matt Hargett, Principal Software Engineer / Roblox - [5x Faster message sending time](https://www.callstack.com/case-studies/enhancing-applications-performance-for-expensify) - ISO 27001 certified Case studies ## What shipping at AI speed looks like. ### [Building scalable observability for a high-growth React Native app](https://www.callstack.com/case-studies/building-scalable-observability-for-a-high-growth-react-native-app) Agentic Delivery · Finance **3→1** analytics systems unified into a single interface ### [Launching a High-Performance React Native app on Samsung TV](https://www.callstack.com/case-studies/launching-samsung-tv-app-for-global-streaming-platform) Expert Engineering · Media & Streaming **5** platforms under one RN codebase: tvOS, FireTV, Tizen, LG, Vizio ### [Speeding Up Android and iOS Builds Without Compromising Banking Security](https://www.callstack.com/case-studies/cutting-mobile-build-times-by-up-to-79-for-a-southeast-asian-bank) Expert Engineering · Finance **2.4×** faster iOS cache-hit builds on average ### [Building Storybook Connect for JetBrains Twice as Fast With AI](https://www.callstack.com/case-studies/building-storybook-connect-for-jetbrains-in-25-working-days) Expert Engineering · DevTools **2×** Estimated AI-assisted delivery speedup ### [A brownfield architecture that kept feature delivery moving across financial apps used by millions](https://www.callstack.com/case-studies/modernizing-mobile-apps-in-production-with-react-native-and-self-hosted-ota) Expert Engineering · Finance **4x** increase in RN pages across the tracked page set ### [Building an Agentic SDLC for a Web Launch in Under One Month](https://www.callstack.com/case-studies/building-an-agentic-sdlc-for-a-web-launch-in-under-one-month) Agentic Delivery · Software Development **3x** estimated delivery acceleration ### [AI-Assisted Design-to-Code Delivery Across Web and Mobile](https://www.callstack.com/case-studies/engineering-ai-loops-for-a-cross-platform-design-system) Expert Engineering · Software Development **60+** components mapped with full Code Connect coverage ### [Enhancing Expensify app performance](https://www.callstack.com/case-studies/enhancing-applications-performance-for-expensify) Expert Engineering · Finance **5x** faster message sending time ### [Teamworks cut mobile change lead time from days to minutes](https://www.callstack.com/case-studies/accelerating-teamworks-mobile-delivery-with-re-pack-and-module-federation) Expert Engineering · Sports & Entertainment **10** min from code change to mini-app release ### [React Universe App: Networking evolved with Liquid Glass](https://www.callstack.com/case-studies/react-universe-app-networking-evolved-with-liquid-glass) Expert Engineering · Software Development **63%** adoption rate; majority of attendees registered in the app ### [Migrating Questrade Edge Mobile to a Faster, More Scalable Architecture](https://www.callstack.com/case-studies/migrating-questrade-edge-mobile-to-a-faster-more-scalable-architecture) Expert Engineering · Finance **33%** fewer re-renders across most features ### [Migrating a legacy React Native app to Expo](https://www.callstack.com/case-studies/migrating-a-legacy-react-native-app-to-expo-for-faster-builds-and-simplified-releases) Expert Engineering · Retail & E-commerce **6x** faster builds after replacing Jenkins with EAS ### [Training HelloFresh engineers to build production apps with React Native](https://www.callstack.com/case-studies/training-hellofresh-engineers-to-build-production-apps-with-react-native) Expert Engineering · Retail & E-commerce **2.8x** increase in knowledge over 8 weeks (25% → 71% assessment scores) ### [Building a browser-based React Native playground](https://www.callstack.com/case-studies/building-a-browser-based-react-native-playground-for-expo) Expert Engineering · Software Development ### [Migrating From Native to React Native Without Slowing Down Delivery](https://www.callstack.com/case-studies/migrating-ios-and-android-apps-to-react-native-for-autozone) Expert Engineering · Automotive **2x** growth in mobile user base during the migration period ### [Optimizing Android TV startup by disabling JS bundle compression](https://www.callstack.com/case-studies/optimizing-android-tv-startup-for-global-streaming-platform) Expert Engineering · Media & Streaming **5%** faster startup time on FireTV and FireHD devices ### [Migrating to Next.js for better performance and SEO](https://www.callstack.com/case-studies/migration-to-nextjs-for-autozone) Expert Engineering · Automotive **#1** SEO rank, recovering from 3-9 ### [Improving Chat Performance and Creating a Custom UI Library](https://www.callstack.com/case-studies/improving-chat-performance-for-dream11) Expert Engineering · Sports & Entertainment **78%** bundle size reduction (from 50 MB to 11 MB) ### [Creating React Native SDK wrapper](https://www.callstack.com/case-studies/creating-react-native-sdk-wrapper-for-rive) Expert Engineering · Software Development **100k** weekly downloads on npm ### [Improving performance of Super App](https://www.callstack.com/case-studies/improving-performance-of-super-app-for-momo) Expert Engineering · Finance ### [Modernizing React Native codebase and adding platform features](https://www.callstack.com/case-studies/modernizing-react-native-codebase-for-7cup) Expert Engineering · Healthcare **130%** increase in users post-upgrade ### [Launching a white-label Super App](https://www.callstack.com/case-studies/launching-white-label-super-app-for-zephyrcloud) Expert Engineering · Software Development Clients ## Trusted by enterprise teams at scale. > The team at Callstack are the most experienced engineers in the React Native community. > > — Nader Dabit, Senior Developer Advocate / AWS > If you're looking for skilled and trusted React Native developers, Callstack is definitely the way to go. > > — Tom Occhino, Director of Engineering / Meta > Their engineers proved to be a crucial part of our mobile app relaunch project. > > — Brian Aznar, Engineering Director / MLS > The trainers are always very helpful and supportive. It really makes a difference! > > — Artem Musiienko, Staff Eng / Hello Fresh > I appreciate their attention to detail, flexible approach and a high degree of expertise. > > — Glen Moriarty, Founder and CEO / 7cups > We had been struggling with React Native application performance until we met Callstack. > > — Huỳnh Chí Hùng, Associate Director / MoMo > I recommend them as a trusted tech partner for running complex projects. > > — Jin Chung, Co-Founder, CTO / Rainbow > Teamworks needed Module Federation, we helped make it real > > — Michael Song, Head of Platform / Teamworks > 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 / Expo 10 years of React Native → Now in your AI stack ## Ship your product at AI speed. Senior engineers and agents, building cross-platform products faster without lowering the bar. Let's scope what that looks like for your team. [Book consultation](https://www.callstack.com/contact) Insights ## Worth your time, by engineers. - [React Native Wrapped 2025: A Month-by-Month Recap of The Year](https://www.callstack.com/blog/react-native-wrapped-2025-a-month-by-month-recap-of-the-year) (Article, 10/16/2026): The first edition of React Native Wrapped looks back at the year RN turned 10 and the ecosystem doubled down on the New Architecture. It provides a month-by-month record of 2025, covering major framework releases, the Legacy Architecture freeze, React 19 integration, and notable developments across tooling, performance, styling, native modules, Expo, and platform adoption. - [Efficient On-Device LLMs in React Native Done Right](https://www.callstack.com/events/efficient-on-device-llms-in-react-native-done-right) (Event, 11/17/2026) - [MCP and Supervisor Agents in eBay's Monitoring Workflow With Leonel Candido da Silva](https://www.callstack.com/podcasts/mcp-and-supervisor-agents-in-ebays-monitoring-workflow-with-leonel-candido-da-silva) (Podcast, 10/13/2026) - [Behavior Review for AI-Native Delivery](https://www.callstack.com/events/behavior-review-for-ai-native-delivery) (Webinar, 7/21/2026) - [Your AI Coding Agent Still Needs an Architecture](https://www.callstack.com/blog/your-ai-coding-agent-still-needs-an-architecture) (Article, 10/22/2026) [Explore Insights](https://www.callstack.com/insights)