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𝐀𝐥𝐥 𝟓-𝐒𝐭𝐚𝐫 𝐑𝐞𝐯𝐢𝐞𝐰𝐬.🌟 𝐓𝐨𝐩 𝐑𝐚𝐭𝐞𝐝 🌟 • 𝐓𝐨𝐩 𝟏𝟎% 𝐨𝐟 𝐔𝐩𝐰𝐨𝐫𝐤 𝐅𝐫𝐞𝐞𝐥𝐚𝐧𝐜𝐞𝐫𝐬 🥇 A Senior Fullstack & Mobile Developer with over 12 years of experience delivering high-quality software solutions for web and mobile applications. I have successfully built and launched 30+ mobile apps, many of which are live in the App Store and Google Play. I do not just write code — I help clients move their product from idea, MVP, or existing web app to a real mobile app that can be tested, submitted, and launched. I help founders, startups, and businesses build, fix, and launch production-ready mobile apps for the App Store and Google Play. With 12+ years of software development experience and 30+ launched mobile apps, I specialize in iOS, Android, cross-platform mobile development, backend integration, in-app purchases, authentication, AI-powered features, and app store release support. My strongest areas include: ✅ iOS development with Swift, SwiftUI, UIKit, and Objective-C ✅ Android and cross-platform apps with Flutter, React Native, Expo, and Capacitor ✅ App Store and Google Play submission, TestFlight, internal testing, closed testing, and review issue fixes ✅ In-App Purchases, subscriptions, RevenueCat, Superwall, Stripe, and payment flows ✅ Supabase, Firebase, Firestore, PostgreSQL, MySQL, MongoDB, and backend integrations ✅ Apple Sign-In, Google Sign-In, Firebase Auth, Supabase Auth, and social login flows ✅ AI app development using OpenAI API, Claude, DeepSeek, and other AI integrations ✅ Push notifications, APNS, FCM, maps, background location, Bluetooth, and real-time features ✅ Existing app maintenance, performance improvement, bug fixing, and production issue resolution I can help you with: - Turning web apps, Lovable, Bolt, Replit, FlutterFlow, Base44, or existing MVPs into iOS and Android apps - Building complete iOS and Android apps from scratch based on designs created in Figma, Adobe XD, or Sketch - Turning UI/UX designs into pixel-perfect, responsive mobile applications - Developing complete backend systems, databases, APIs, authentication, and admin dashboards - Handling the complete development lifecycle—from UI implementation and backend development to testing and App Store/Google Play release - Preparing iOS and Android builds for TestFlight and Google Play testing - Fixing App Store and Google Play rejection issues - Setting up subscriptions, paywalls, free trials, and restore-purchase flows - Integrating Supabase, Firebase, RevenueCat, Stripe, OpenAI, and other third-party services - Building AI-powered mobile features such as chat, analysis, content generation, voice interaction, and automation - Improving existing apps, fixing production issues, and preparing them for release Tech stacks I work with: Mobile: Swift, SwiftUI, UIKit, Objective-C, Flutter, Dart, React Native, Expo, Capacitor, Android Backend: Java, Spring Boot, Go, Gin, Python, REST APIs, WebSocket, microservices Database & Cloud: Supabase, Firebase, Firestore, PostgreSQL, MySQL, MongoDB, SQLite, Redis, Google Cloud, AWS Payments & Subscriptions: RevenueCat, Superwall, Stripe, Apple IAP, Google Play Billing AI & Automation: OpenAI API, Claude, DeepSeek, AI-assisted app features, AI workflow integration I focus on clean implementation, reliable communication, and practical solutions that help your product move forward. Whether you need to launch a new app, fix an existing one, add subscriptions, solve login issues, or pass app review, I can help you get it done properly. If you need a developer who understands both mobile development and the full release process, I’d be happy to help.

Hello, I am a front-end developer with experience in Vue, HTML, CSS, JavaScript, Uniapp, and Mini Program. I am also proficient in using jQuery and creating animated pages. Web dev In addition to mobile app development, I am an experienced web developer who focuses on creating beautiful and responsive web pages. I master multiple web technologies such as HTML, CSS, JavaScript, and vue, and prioritize user experience and page performance. If you need to develop stunning and responsive web pages or other related projects, please feel free to contact me. As a front-end developer, I am passionate about creating engaging and user-friendly interfaces for web and mobile applications. With my expertise in Vue, HTML, CSS, and JavaScript, I can bring to life even the most complex designs and interactions. In addition, I have experience with Uniapp and Mini Program, which are essential for creating cross-platform mobile applications. I have worked on a variety of projects that required the use of these technologies, and I am confident in my ability to deliver high-quality results. My skills in jQuery also allow me to create dynamic and interactive user interfaces that enhance the overall user experience. And when it comes to creating animated pages, I am well-versed in using CSS and JavaScript to create stunning visual effects that captivate and engage users. Overall, I am a dedicated front-end developer with a passion for creating exceptional user experiences. I am always eager to learn and grow, and I look forward to bringing my skills and expertise to your next project.

I’m a Senior Full-stack and Mobile Engineer based in China. With over seven years of experience, I specialize in developing scalable web and mobile applications and AI Orchestration. Languages: C++ / JavaScript / TypeScript / Python / Java / Go / Swift Frontend: React / Vue.js / Next.js / Angular / Tailwind CSS Mobile: React Native / Flutter / iOS (Swift) / Android (Kotlin) Backend: Node.js / Express / Django / Spring Boot / GraphQL Cloud: AWS / GCP / Azure / Docker / Kubernetes AI / ML: LLM / OpenAI API / LangChain / RAG / Hugging Face / PyTorch Developed cross-platform applications using Flutter and React Native, achieving over 200,000 downloads. Designed a microservices architecture using Node.js and AWS Lambda, capable of handling over 50,000 Daily Active Users (DAU). Implemented push notifications and offline synchronization features, resulting in a 35% improvement in user retention rates. Integrated LLM-based features into applications by leveraging the OpenAI API and RAG. Developed blockchain-enabled mobile game applications (featuring Web3 integration and wallet connectivity). Published three applications to the App Store and Google Play, maintaining a crash-free rate of 99.5%.

I help startups and businesses build, launch, and scale high-quality mobile applications for iOS and Android. With 15+ years of mobile development experience and 10+ years specializing in React Native, I've delivered production applications used by hundreds of thousands of users and generated over $500,000 on Upwork through long-term client partnerships. Whether you need to build a new product from scratch, improve an existing application, or solve difficult technical issues, I can take ownership of the entire mobile development lifecycle. What I can help you with ✅ React Native & Expo Development ✅ Cross-platform iOS & Android Apps ✅ MVP Development for Startups ✅ AI-powered Mobile Apps (OpenAI, Claude, Gemini) ✅ Firebase & Supabase Integration ✅ Push Notifications ✅ In-App Purchases & RevenueCat ✅ Stripe Payments ✅ Authentication & Social Login ✅ Maps, GPS & Location ✅ Camera, QR Code & Media Processing ✅ Chat & Real-time Messaging ✅ Performance Optimization ✅ Crash Investigation & Bug Fixing ✅ App Store & Google Play Release My experience Before freelancing, I worked as a Senior Mobile Engineer at Haier (Fortune Global 500), where I participated in developing and maintaining more than 100 mobile applications, including products with over one million users. Later, I joined a US startup as the lead React Native engineer and built the company's cross-platform mobile application from scratch. I was responsible for architecture, feature development, payment systems, live streaming, creator features, app performance optimization, and long-term product maintenance. Today, I primarily work with startups and established companies to build reliable, scalable mobile products that are ready for production. Why clients work with me ✔ 500K+ earned on Upwork ✔ 10,000+ development hours ✔ Long-term client relationships ✔ Clean, maintainable code ✔ Excellent communication ✔ Fast response time ✔ Strong debugging and performance optimization skills ✔ Able to work independently with minimal supervision If you're looking for someone who can build, improve, or maintain a production-ready mobile application—not just write code—I'd be happy to discuss your project. Let's build something great together.

✅ 13 Years Professional Experience ✅ 40+ Mobile Apps ✅ Top Rated Plus Developer Hey there! 👋 I'm Sherwin, an expert Engineer with 13+ years of experience at big tech companies. I'm experienced leading, designing and implementing core mobile features in fast-paced, technology-driven environments with worldwide impact and multiple stakeholders. I am fluent in English and have experience working with scalable and testable code, REST APIs, multiple design patterns, CI/CD pipelines and version control. 🏆 Worked in the multinational company MicroStrategy, Developed apps with over 100 million daily users such as DiDi and Kuaishou before. 🚀 Expertise in Technologies: o Native Development: Swift, SwiftUI, Objective-C, Kotlin, Java, Jetpack Compose, HarmonyOS o Cross-Platform Frameworks: React Native , Flutter o DataBase: Realm, CoreData, Firebase FireStore, Firebase Realtime Database, Supabase, RoomDatabase o Web: Flutter Web o Deploy: AWS S3, Lamda, CloudFront, EC2, OpenShot o Server Development: Python, TS ✅ My experience domains: o AI Agent o Bluetooth / Smart Watch / Camera Domain o Fitness / Health Domain o OpenAI / Assistance / Whisper o Location Tracking / Travel o Social Media/Dating Domain/Video/Audio chats o Video/Audio player processing application o Financial / Shopping Domain o Payment / In App Purchase / Apple Pay / Stripe I'm excited to bring my experience and skills to new projects and deliver high-quality work on time and within budget. Let's make great apps together! Regards, Shaolin

Everyone is watching to see how fast and satisfying it is to execute projects using AI—how even those without an IT background can accomplish so much on their own. Yet, people often overlook the value of industry expertise and the importance of using AI correctly to accelerate workflows without compromising quality. This is the realm of Rolls-Royce, Koenigsegg, and fine Italian furniture: we embrace innovation, but we prioritize quality above all else. **TOP RATED PLUS** TOP 3% Of Upwork Freelancers By QUALITY Bottom 50% by PRICE. Experienced professional in offshore development with over 18 years working with a US company, 20+ years exp in IT industry. Areas of expertise: web development, application development, native mobile app development. NDA can be signed upon client request. With experience in the education, banking, non-profit, medical and business world on-and-off upwork, we offer our clients efficient and accurate output of the highest standard, saving them time and money, delivering the desired results, and often surpassing their expectations. =====BELOW ARE SOME KEYWORDS FOR YOU TO FIND ME HERE===== Professional Skills - Languages: PHP, SQL, BASH, HTML5, JavaScript, XHTML, CSS, XML, JSON, VUE - OS: Linux (CentOS/Ubuntu), OSX, Windows series; - Administration: Apache, UNIX Shells/Scripting; - Database: MySQL, MongoDB; - Technologies: MVC, jQuery, Bootstrap/Foundation, CodeIgniter / Yii /Laravel Framework, SVN/Git, Smarty, PEAR; - IDE: PHPStorm, NetBeans, Zend Studio; - 3rd part API: Facebook, AWS, Google Maps, Flickr, Payflow and Twitter, Youtube/Vimeo, Google Doc, Mailgun, Mailchimp, AliPay, WeChat, etc - 2nd developing: Joomla!, WordPress, Durpal, SugarCRM, ZenCart, VanillaForum, OpenCart, osC; - PCI Complaince, ADA Complaince, Section 508 - Knows Basic HIPPA laws for website and web application level. Willing to use scanners to help application to pass HIPPA complaince. - Wechat Mini Programm. WeChat Work. WeCom, WeChat Official Account Programing/Customizations. weixin Summary/Highlights: - Good at PHP programming, 10 years of PHP programming experience, and 7 years of web front-end programming experience. - Agile web development experience, TDD; - CSS pixel-level layout consistency with browser, version and platform independence, can solved cross browser/platform and device compatibility issues. - Good at responsive layout; - Smoothly use MVC framework for PHP developing, good at CodeIgniter/Laravel/Yii/Kohana framework; - Have strong knowledge of AWS (EC2, S3, SNS, etc.) APIs and have implement experience; - Design and implement of the Web Crawler(based on CURL lib), tens of millions of data crawl experiences; - Code optimization for SEF/SEO; - Solve XSS/CSRF issues experience; - Deploy and maintains production server (LAMP and Control Panel) experience; - Code optimization for load speed and render speed; - Offsite Backup/Recovery system experience; - Experience working with CI/CD tools like Jenkins. - Fluent English and Chinese/Mandarin.