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I don't just write React Native code. I ship apps people actually use. 1M+ downloads. 30+ countries. 200+ projects. 100% Job Success. Most clients come to me when their React Native app is stuck, broken, or half-built and nobody else could finish it. Or when they need a mobile app developer who handles everything from first screen to App Store and Google Play launch. Some come with an MVP idea and need a react native developer who moves fast without cutting corners. Others come because their react native mobile app has performance issues or complex integrations nobody else could solve. I've been doing this for 8+ years, delivered 200+ projects, and the apps I've built as a mobile app developer now serve 590K+ users across 30+ countries. WHAT I BUILD As a react native developer and react native engineer I cover the full mobile lifecycle across 200+ shipped products: ✦ React Native mobile apps with Expo and CLI for iOS and Android ✦ React Native Expo MVPs shipped from first screen to App Store and Google Play ✦ React Native Firebase integrations — auth, Firestore, real-time sync, push notifications ✦ React Native Supabase backends and React Native Node.js APIs that scale with the product ✦ AI mobile app development with OpenAI API, real-time features, and on-device intelligence ✦ In-app purchases, RevenueCat subscriptions, AdMob, deep linking, and push notifications ✦ Native Swift and Kotlin modules and android kotlin integrations when cross-platform isn't enough ✦ App Store and Google Play submissions including rejections, TestFlight, and review handling I work as a react native full stack developer so clients don't need to hire two separate people. Firebase, Supabase, and Node.js on the backend — one team, one codebase, one point of contact. INDUSTRIES I've shipped products as a mobile app developer and mobile application developer across multiple verticals. In Fintech and Crypto I built a trading platform with 590K+ registered users and 2M+ monthly visitors. In Healthcare and Wellness I delivered apps with 100K+ downloads, a 4.9 App Store rating, and users across 30+ countries. In EdTech I shipped language learning and trivia apps that together reached 1M+ downloads. I've also delivered E-commerce, SaaS MVPs, Hospitality, and On-demand platforms: ✦ Fintech and Crypto — 590K+ users, 2M+ monthly visitors ✦ Healthcare and Wellness — 100K+ downloads, 4.9 App Store rating, 30+ countries ✦ EdTech — 1M+ downloads across 30+ countries ✦ E-commerce and Marketplace ✦ SaaS and Startup MVPs ✦ Hospitality and On-demand Services WEB AND FULL STACK On the web side I work as a react developer and front end developer building platforms with React, Next.js, and Node.js. I've delivered react nextjs products, full stack developer react node systems, and full stack developer ai projects with LLM integrations and OpenAI workflows. I've worked alongside Vue and Angular codebases and helped clients migrate from WordPress to modern React stacks. On larger projects I work as a web developer delivering both mobile and web from the same team. Clients who need an app developer ios android with full backend ownership also work with me on ios android developer projects. I collaborate with flutter developer and android developer teams when needed, and I structure codebases that a python developer or backend node.js team can extend later. WHY CLIENTS WORK WITH ME ✦ 8+ years as a react native developer and mobile app developer — 200+ projects, 1M+ downloads, 30+ countries ✦ React native full stack developer — mobile frontend and backend in one engagement ✦ Fast at complex bugs, App Store rejections, and performance issues others couldn't fix ✦ Clear written communication and honest timelines, no surprises ✦ Available after launch for support, new features, and scaling WHAT CLIENTS SAY "Michael is an outstanding react native developer — skilled, reliable, and delivers clean, efficient code." "Succeeded on complex React Native bugs where others failed." "Exceeded our expectations." If you're looking for an experienced react native developer and mobile app developer who gets things shipped — press Invite or send a message.

💻 Senior Frontend Developer | React, Next.js, React Native (Expo), Angular, Vue.js With over 10 years of experience in frontend development, I specialize in building modern, scalable, and user-focused web and mobile applications. My expertise includes React, Next.js, Angular (2+), Vue.js, and React Native (Expo), with a strong focus on performance, clean architecture, responsive design, and seamless user experiences. I enjoy transforming complex business requirements into intuitive, high-quality digital products. 🚀 Expertise in: 📱 React(Next.js, Vite, MUI, RHF, Zustand, Tanstack) 📲 React Native (Expo): Building dynamic web and mobile applications 🌐 Modern Frontend Frameworks: Proficient in React, Angular 2+, Vue.js, and Next.js for responsive, scalable web development 🔧 Backend Knowledge: Familiar with PHP (Laravel, Slim, Lumen) and Node.js for basic backend integration 🛒 CMS & E-Commerce: Expertise in WordPress, WooCommerce, Plentymarkets, Magento theme/plugin development, and custom integrations ✨ Clean, Efficient Code: Passionate about writing maintainable and scalable solutions for a smooth user experience 🔗 API Integration: Skilled in SOAP/RESTful API development and integration for seamless client connectivity Let’s create high-quality, intuitive apps and websites that stand out and drive results! 💻 𝙎𝙚𝙖𝙧𝙘𝙝 𝙛𝙤𝙧 𝙢𝙚 𝙪𝙨𝙞𝙣𝙜 𝙩𝙝𝙚𝙨𝙚 𝙠𝙚𝙮𝙬𝙤𝙧𝙙𝙨: React, Angular, Vue.js, JavaScript, TypeScript, Next.js, Nuxt.js, MUI, Zod, RHF, Zustand, Tanstack, Node.js, React Native, Expo, EAS, Php, Twig, HTML5, CSS3, SCSS, Less, Bootstrap, Tailwind, Swagger, OAuth, JWT, WebSockets, SignalR, Ajax, Ecommerce, Web Application, Website Redesign, Git, API, REST API, API Integration, Web Development, Frontend Development, Mobile App Development, iOS, Android

👋 Hello! I'm a Senior Full-Stack and React Native Developer with 7+ years of experience shipping web and mobile products with AI integrations, clean architecture, and reliable production delivery — across healthcare, edtech, and social networking. My core stack includes React Native, Expo, React.js, Next.js, Node.js, TypeScript, JavaScript, Nest.js, Express.js, REST API, GraphQL, PostgreSQL, MySQL, MongoDB, Firebase, AWS, Docker, CI/CD pipelines, and AI/LLM integrations (OpenAI and others). I work across both mobile and web — building cross-platform mobile apps, web dashboards, admin panels, backend services, APIs, authentication systems, payment and subscription flows, notifications, and real-time features. My recent projects have involved microservice-based backend architectures, secure authentication, payment integrations, robust APIs, and CI/CD pipelines for App Store, Google Play, and web deployments. My expertise includes: 📱 React Native & Cross-Platform Mobile Development - React Native / Expo app development - iOS and Android apps from one codebase - App architecture and feature development - App Store / Google Play release support - Push notifications - Authentication flows - Subscriptions and in-app purchases - Performance optimization - Bug fixing and app maintenance ⚙️ Full-Stack Web & Backend Development - React.js / Next.js web applications - Node.js / Nest.js / Express.js backend development - REST API and GraphQL integrations - PostgreSQL, MySQL, MongoDB - Firebase and AWS services - Admin dashboards and SaaS platforms - CI/CD, Docker, and deployment support 🧩 Architecture & Product Engineering - Clean architecture - Domain-driven design - Microservices - Modular monoliths - Event-driven systems - Scalable API design - Code refactoring and legacy system improvements - Unit and integration testing 🧠 AI Integration & AI-Powered Development - Integrating OpenAI and other AI APIs into web and mobile applications - Building AI-powered features: content generation, intelligent assistants, document automation, personalized recommendations - Hands-on experience shipping AI features in production (healthcare and edtech domains) - Using AI tools in my own development workflow to ship faster — while keeping the same engineering standards and code quality My experience spans healthcare, edtech, and social networking — from AI-powered clinical documentation platforms with EHR integrations, to AI-driven learning apps for kids, to event-based social networking products. Across these projects, I've built real-time data synchronization, payment and subscription flows, authentication and SSO, web admin dashboards, and robust backend services. I focus on long-term product stability, performance, and practical business outcomes — building products that are easy to maintain, extend, and improve over time. Whether you're launching a new product, modernizing an existing one, or extending a complex system, I bring senior engineering, modern AI capabilities, and reliable end-to-end delivery. Let's build something reliable and scalable 🚀

⭐️I`m Senior mobile app developer with 5+ years of experience with React Native and specialize in building mobile apps. I focus on creating clean, reusable, and performance-oriented code. I enjoy learning new things and taking on new challenges. 🏅 My tech stack: • React Native: Android, iOS, Windows, macOS, Expo, CLI, JS, TS, Reanimated, Gesture Handler, Redux, Mobx, mobx-state-tree • Native iOS: Objective-C, Swift, UIKit, SwiftUI, Core Animation/Data/Location • Native Android: Java, Kotlin, Jetpack, Jetpack Compose, RxJava, Dagger 2, Data Binding • API Integrations: ChatGPT, Firebase services, Google Maps, Stripe, In-app purchase, Zoom, etc. • Testing: JUnit, XCTest, Jest, Maestro, Detox • Database and storage: SQLite, Realm, WatermelonDB, Firebase Realtime Database, KeyChain, Keystore, UserDefaults, MMKV. • Other: MVVM, MVI, MVC, MVP, Clean Architecture, SOLID, REST, GraphQL, WebSockets, etc. 🚀 Key Skills: - Problem Solving - Team Collaboration - Mobile Development - Good communication

👋 I'm a Senior Full Stack Java Developer with 20+ years of experience building enterprise software, healthcare platforms, fintech solutions, SaaS products, and mobile applications. As a Java Developer I've built high-load backend systems, REST AP payment solutions document processing platforms, and business applications used by thousands of users. As a Full Stack Developer and React Native Developer I've helped startups and growing companies launch scalable products while maintaining security, performance, and compliance. Throughout my career, I've worked with startups, established businesses, and enterprise clients, helping them transform ideas into reliable software products. My experience covers the entire development lifecycle, from architecture planning and technical discovery to development, deployment, optimization, and long-term support. My expertise includes Java Developer Spring Boot React Native AWS PostgreSQL Docker Kubernetes microservices cloud infrastructure and secure software architecture 💪 Full Stack Java Developer Expertise ✔️ 20+ years of Java development 100 successful projects using Java, Spring Boot, Spring Security, Hibernate, and enterprise architectures ✔️ Full Stack Development covering backend architecture database design frontend implementation and React Native mobile applications ✔️ Spring Boot Development, REST API microservices cloud-native applications and high-performance backend systems ✔️ Backend Architecture, distributed systems, 50 third-party integrations, authentication systems, and secure API development ✔️ PostgreSQL MySQL Redis AWS Docker Kubernetes CI/CD performance optimization and legacy system modernization ✔️ Extensive experience designing business-critical applications where scalability, maintainability, security, and long-term growth are key requirements ✔️ Experience integrating payment gateways, healthcare systems, cloud services, identity providers, and external enterprise platforms ✔️ Strong understanding of software architecture, design patterns, clean code principles, and modern development practices ✔️ Experience leading technical initiatives, collaborating with distributed teams, participating in code reviews, and helping businesses make technology decisions 🏥 Healthcare Software Development Expertise As a Senior Java Developer and Full Stack Developer I've built secure and HIPAA compliant healthcare software for startups clinics and digital health companies ✔️ EHR / EMR systems, telemedicine platforms, patient portals, and patient engagement applications ✔️ FHIR & HL7 integrations for healthcare interoperability and secure data exchange ✔️ React Native healthcare applications with Apple HealthKit Google Fit BLE integrations and real-time health monitoring ✔️ Improved patient engagement by up to 100% ✔️ HIPAA compliant architectures with encrypted storage, audit logging, role-based access control, and secure API ✔️ Java Spring Boot backend systems with up to 99.9% uptime ✔️ Healthcare workflow automation, provider portals, appointment management systems, and patient communication platforms. 💳 Fintech Software Development Expertise As a Full Stack Java Developer I've built PCI DSS-compliant fintech platforms focused on payments, identity verification, and transaction security. ✔️ Stripe Apple Pay Google Pay and 3D Secure ( 3DS ) integrations ✔️ KYC & AML workflows for onboarding and compliance automation. ✔️ Reduced payment default rates in more than 100+ projects ✔️ Payment processing platforms, transaction management systems, and financial API ✔️ Secure fintech architectures with encrypted storage, tokenization, audit logging, and secure authentication. ✔️ Financial reporting systems, payment workflows, transaction monitoring, and compliance-focused software solutions. 🏆 Key Results ✔️ 15+ years of commercial software development experience. (role Full Stack Java Developer ) ✔️ Built enterprise healthcare fintech and SaaS applications for startups and growing businesses ✔️ Achieved up to 100% uptime for mission-critical systems. ✔️ Improved patient engagement by up to 40% ✔️ Reduced payment decline rates by up to 25% ✔️ Improved application performance by up to 35% ✔️ Reduced infrastructure costs by up to 25% ✔️ Reduced security vulnerabilities by up to 90% ✔️ Modernized legacy applications through microservices adoption and cloud migration initiatives 📌 Core Technologies Java Developer • Spring Boot • Spring Security • Hibernate • React Native • TypeScript • PostgreSQL • MySQL • Redis • Kafka • AWS • Docker • Kubernetes • REST API • Microservices • FHIR • HL7 • HIPAA • PCI DSS • Stripe • KYC • AML 📩 Looking for a technical partner who understands both technology and business goals? I help companies build, scale, and modernize Healthcare Fintech SaaS and Enterprise products using Java Spring Boot Full Stack technologies and React Native If you're looking for more than just code, let's discuss your project and how I can help.

Need a mobile app built that holds up after launch? I lead mobile app development that ships production-ready iOS and Android apps that survive real users - several are live on the App Store and Google Play right now. I'm Oleksandr, founder and lead engineer at Kultrix, an AI and Mobile App Studio, working from Lviv. Most of our work is React Native mobile app development, plus the AI features and backend that make an app actually useful. I run engagements as a long-term technical partner, not a vendor you chase for updates - which is why several engagements have run 16 months to 4+ years. You get senior engineering ownership from first call to store release: clear scope, milestone-based delivery, honest timelines, and a lead who is accountable for the result. As founder and lead engineer, I make sure the mobile app development gets done right, not just fast. WHAT WE BUILD - Full mobile app development in React Native and Expo, from idea to store release - a cross-platform iOS and Android app from one codebase, typically a launched MVP in 6-10 weeks. With a senior React Native developer leading, we cover MVP development, App Store and Google Play submission, and everything in between. - AI integration inside mobile apps - chat, image and vision analysis, and conversational voice (OpenAI and Anthropic Claude), already shipped in live AI mobile apps. Clean API integration so the AI feature feels native, not bolted on. - Rescue and refactor of React Native apps that broke under real users - performance, crashes, and stability work to get an existing app back to store-ready. - Backend when your app needs more than screens: Node.js, NestJS, Python and FastAPI, PostgreSQL, MongoDB, Firebase, and Supabase (including auth and RLS). WHO IT IS FOR - Starting from scratch: a clear path from idea to a launched MVP in 6-10 weeks, built by a team that has shipped to both stores. - Already have an app: mobile app development help with new features, performance, and stability - whether you need an iOS developer, an Android developer, or both. - Want to add AI: a chat, vision, or voice feature shipped into your live cross-platform app through careful AI integration, scoped so it ships fast and stays maintainable. HOW WE WORK You talk to the people building your app, not a sales layer. We agree on scope and milestones up front, you see working builds early and often on TestFlight and internal tracks, and you get honest status instead of silence. When something is harder than estimated, you hear it early - with options, not surprises. The goal is a stable app you can grow on, and a codebase your next mobile app developer can read without a rewrite. VERTICALS WE KNOW We have shipped mobile app development work across health and wellness, nutrition, and fitness (calorie tracking, meal analysis, AI coaching), fintech and Web3 (payments, Plaid, Polygon on-chain apps), SaaS (Stripe billing and dashboards), and internal tools and logistics (warehouse and operations systems). If your app lives in one of these spaces, we have built and launched something close to it. RESULTS - An AI nutrition tracker - React Native meal and calorie analysis with Anthropic Claude and OpenAI - live on both the App Store and Google Play, owned end to end (mobile, API, and admin). - An AI fitness app on a Python and FastAPI backend with OpenAI, live on the App Store and Google Play. - A conversational-voice health app built with React Native, Expo, and Claude. - A Web3 scratch-card app on Polygon with Plaid integration, live on Google Play, plus a daily-quotes app on the App Store. - A warehouse operations system that runs 4x faster for 100+ employees. - Long-term mobile app development engagements kept for 16+ months and 4+ years - the clearest signal that this work lasts. OUR STACK React Native, Expo, TypeScript for cross-platform iOS and Android; Node.js, NestJS, Python and FastAPI, PostgreSQL, MongoDB, Firebase, and Supabase on the backend; Stripe, in-app purchases, push notifications, and WebSockets for real product features; and AI APIs (OpenAI and Anthropic Claude) for chat, vision, and voice. This is the full toolkit for modern mobile app development and AI integration, from first commit to a stable app on the App Store and Google Play. Send me your idea or your existing app and you will get back a clear, honest breakdown - what to build first, what can wait, and a realistic timeline for the mobile app development. No pressure, no jargon, just a straight answer from the lead who would own the work. Oleksandr - founder and lead engineer, Kultrix (AI and Mobile App Studio).