Hire the Best App Development Freelancers
in Vietnam

Are you looking for a seasoned expert in cross-platform mobile app development using Flutter? Look no further! 🔧 My Expertise: I excel in crafting high-quality cross-platform mobile apps using Flutter. I am well-versed in various design patterns, including BLoC, Provider, and GetX, and I'm fluent in programming languages such as Dart, Swift, Java, Objective-C, and JavaScript. Additionally, I have extensive experience with essential mobile frameworks like In-App Purchases, Maps, Camera, and Push Notifications. 📦 Third-Party Integration: I bring a wealth of experience in integrating third-party SDKs, making your app feature-rich and interactive. Some of the SDKs I've successfully integrated include Facebook, Stripe, Google Maps, AdMob, and more. 📊 Quality and Scalability: My commitment to quality is unwavering. I create apps that are not only responsive but also rigorously tested across a wide range of devices. I pride myself on delivering well-architected, well-documented, and easily maintainable projects, ensuring that your app can grow and adapt as your company does. ✅ My Skill Set: Languages: JavaScript, Dart, Java, Swift, Objective-C Platforms: Flutter, Android, iOS Familiar with SDKs & Tools: Firebase, Stripe, Mapbox, Google Maps, Facebook, Twitter, LinkedIn, and more Environments: Proficient in Windows and MacOS Version Control and Project Management: Bitbucket, Github, Jira, Trello, and others 💼 Let's Collaborate: If you're looking for a Flutter developer who can turn your app ideas into reality, I'm ready to discuss your project and bring it to life. My commitment to excellence and a track record of successful projects make me the ideal choice for your mobile app development needs. Let's build something great together!

I help startups and businesses build high-quality mobile apps using Flutter and FlutterFlow — from MVP to production-ready product — with a dedicated team behind me to move fast and ship reliably. Beyond mobile, I bring a strong focus on AI-native development: using tools like Claude, Cursor, and AI agents not just as coding assistants, but to automate business workflows, clarify requirements faster, and reduce development time significantly. My strength is knowing where AI creates real productivity gains — and where traditional engineering is still the right call. With 20+ years in software development and experience serving clients across Japan, the US, Australia, and Asia Pacific, I understand how to work across different business cultures, communication styles, and project expectations. ✅ CORE EXPERTISE: ・Mobile: Flutter, FlutterFlow, React Native ・AI / LLM: OpenAI API, Claude, Dify, RAG, LangChain, n8n ・Backend: Ruby on Rails, Node.js, Python ・Cloud: Firebase, Supabase, AWS, Google Cloud ・Low-code: FlutterFlow, Bubble, Kintone ✅ DOMAIN EXPERTISE: ・Mobile Apps & Cross-platform Development ・AI-powered Applications & Workflow Automation ・SaaS & MVP Development ・Booking & Reservation Systems ・E-commerce & Marketplace ・Healthcare & Wellness Apps ・Real Estate & Property Management ・HRTech & Job Matching

✅ TOP RATED PLUS (Top 3% Freelancer) Developer on Upwork, specializing in Mobile (Android native/Flutter). A pioneering and security-oriented developer offering more than 14 years of experience designing, implementing, integrating, testing and supporting impactful applications developed in diverse, collaborative environments for mobile and tablet devices on the mobile platform. WHY CHOOSE ME? ✅ 14+ Years of experience in Mobile Development ✅ 50 Finished Projects on Upwork, 100% Job Success ✅ 99% Clients who would recommend ⚡️ROCKSTAR IN: — Native Android/IOS Development — Hybrid Mobile Development - Flutter/React Native — Rust/NodeJS Backend Development ✅ Career Highlights - Developed numerous intuitive, visually engaging, and high-performance mobile applications that prioritize user experience and functionality. - Recognized for writing clean, efficient, secure, and reusable code, with a strong focus on privacy and data security. - Skilled in object-oriented design, data structures, problem-solving, performance optimization, and advanced debugging techniques. - Deep expertise in handling device compatibility and cross-version behavior across the mobile ecosystem. - Known as a self-driven, organized, and reliable developer who consistently meets deadlines and delivers quality work. - Provided technical leadership and mentorship to junior developers, helping elevate team performance. - Active contributor to the developer community with over 8,200 reputation points on Stack Overflow. 💬REVIEWS FROM CLIENTS: ⭐⭐⭐⭐⭐ "Phuoc Doan Hong is a true expert. His Kotlin knowledge and Android development experience are really valuable. I highly recommend this guy." ⭐⭐⭐⭐⭐ "He was an expert, in every move he made. Knowledgeable, patient and easy to communicate with. You can blindly trust him. Thanks again" ⭐⭐⭐⭐⭐ "Doan is highly skilled, smart, and works hard to find the best solution for complex problems. He has deep understanding of performance considerations in the Android platform. An Android expert. His English is excellent, and communication is great." ⭐⭐⭐⭐⭐ "I can simply say that I am very happy to work with him. He is very responsible, hardworking, and talented developer with great communication skills. He understood all the problems and delivered clear solutions. His skills and his professionalism are very high level. I am sure we will be working on new projects with him. Thanks for this amazing work!" Below you will find client reviews section, it describes the quality of work and value that you can expect from working with me

Most dev shops ship isolated features. We build the core systems that run your day-to-day operations, and we stay accountable for outcomes, not just output. I'm Jack, CEO of NUS Technology. Since 2013 we've been a co-located team in Vietnam building operations platforms, integrations, and automation for founders and operators across Australia, the US, and Europe, on products where performance, maintainability, and business alignment actually matter. WHY CLIENTS CHOOSE US - Top Rated Agency on Upwork, 98%+ Job Success Score since 2013, 4.8/5.0 average rating - $10M+ in project value delivered - Long-term partnerships: many clients have worked with us for 5-10+ years - 90+ people co-located: 60+ web developers, 15+ mobile developers, plus QA, BAs, PMs, and designers WHAT WE DO BEST Operations platforms (our core) We design the central system that orchestrates bookings, payments, teams, hardware, and compliance into one seamless operation: software that bends to your process, not the other way around. We handle the integrations Zapier can't and SaaS avoids: deep data synchronization, legacy platforms, and compliance-grade audit trails where failure isn't an option. Everything that supports it - Web: Ruby on Rails (deep expertise, high-traffic systems, complex domains), React, Next.js, Vue.js, TypeScript, Node.js, PHP (Laravel, Symfony), Python (Django, Flask), REST and GraphQL APIs - Mobile: native (Swift, Kotlin) and cross-platform (React Native, Flutter) - Cloud & DevOps: AWS, Google Cloud, Heroku, CI/CD, Docker, monitoring, cost and scale tuning - eCommerce: Shopify (themes, apps, API integrations, migrations), Spree, Saleor, and custom builds HOW WE WORK - Outcome-driven: we focus on business results, not just shipping code - Ownership mindset: we act like a technical co-founder, not a contractor - Proactive: we surface technical debt and scaling bottlenecks before they escalate - Clear communication across time zones (we're GMT+7, with strong overlap for AU and partial US/EU) - Long-term thinking: we build systems that scale, not quick hacks that break later HOW YOU CAN WORK WITH US 1. Operations platform development: internal platforms, SaaS, workflow automation, complex integrations, replacing fragmented tools with a unified system 2. Dedicated engineering teams: backend, frontend, mobile, and QA engineers as an extended team, often for multiple years 3. Product development & MVPs: from idea to launch, fast but not fragile If you're looking for a team that thinks beyond code, challenges assumptions, and builds something that actually lasts, let's talk.

I am a professional embedded software engineer with more than 12 years of experience. My current areas of expertise are IoT Applications & Embedded Systems Design, including embedded hardware/software. 𝐌𝐘 𝐒𝐊𝐈𝐋𝐋𝐒: - Know about MCU: Nordic, Silicon Labs, AVR, PIC, ESP, TI CC32xx, ESP32, Qualcomm QCC51xx, etc. - Have experience in programming languages such as C/C++, C#, Java - Solid knowledge of standard interfaces such as I2C, SPI, UART, and CAN. - Have experience using debugging tools such as Segger Jlink, CAN bus analyzer, and Logic analyzer. - IoT devices with wireless connectivity such as LTE, CAT-M1, NB-IoT, LoRa/LoRaWAN, BLE, WIFI, NFC - Good experience in AWS Service, AWS IoT, AWS Shadow, and AWS Jobs. - Good experience in Battery Management Systems based on BQ products from TI. - Good experience with Audio Codec chips. - Experience with AI/ML on Edge Impulse with nRF Connect - True wireless earbuds, headsets and speakers, Bluetooth ® LE Audio standard from Qualcomm: QCC5141, QCC5171, QCC5181,... We have worked with wearable devices and medical devices: - ECG 1, 3, 12 leads with ADS1292, ADS1293, ADS1298 - EEG with ADS1299 - Body temperature with MAX302025, MAX30208 - PPG with MAX86178, MAX86178 - SPO2 with OB1203, MAX32664 sensor hub - Vital signal with AFE4950 - OTA firmware update via Bluetooth/WIFI End-to-End Embedded & Hardware Solutions I provide complete product development services — from concept and design through prototyping, firmware, and production — for IoT, wearables, medical, and consumer electronics. Hardware & PCB Design - Multi-layer PCB design for high-reliability, high-performance systems - High-speed design: USB 2.0, HDMI 2.0, DDR3/DDR4/LPDDR4, PCIe, NAND Flash, Ethernet (up to 10GBase-T1), PoE++ - Microcontrollers & SoMs: ARM Cortex-M3/M4 (STM32, ESP32, Nordic nRF52/53/91); custom boards for Raspberry Pi CM4, iMX8, Jetson Nano/Xavier/Orin, RK3588/3568, TI AM6254 - Power & analog: DC-DC (Flyback, Boost, Buck, LDO), BLDC/servo motor control, high-resolution ADC/DAC, audio circuits, and battery management (BMS) - DFM/DFA and EMC/EMI compliance, with certification support (CE, FCC, FDA-ready) - Tools: Altium Designer, KiCAD, Eagle, EasyEDA, OrCAD; SolidWorks and Inventor for 3D/enclosure design Firmware & Connectivity - Embedded software in C, C++, Python, and Qt, with RTOS integration and low-power optimization - Custom driver development and communication protocols: QSPI, I2C, SPI, RS485/RS232, CAN, Modbus (TCP/IP/RTU) - Connectivity stacks: BLE, Wi-Fi, NFC, LoRa/LoRaWAN, LTE, CAT-M1, NB-IoT, GSM (3G/4G) IoT platforms: MQTT, ThingsBoard, AWS IoT, Blynk; secure OTA updates, device provisioning, and cloud integration - Robotics: ROS/ROS2 for AGV, AMR, and 6-axis robot applications - Embedded UI/UX: Figma, TouchGFX, LVGL AI & Cloud Integration - Edge AI/ML deployment (Edge Impulse, TensorFlow Lite) - Predictive maintenance and anomaly detection for IoT/IIoT - Cloud integration with AWS, Azure, and Google Cloud - Cross-platform mobile apps (Android/iOS) and web dashboards for monitoring and analytics Product Leadership - Proven experience leading cross-functional teams in startup environments - End-to-end project management across design, fabrication, and procurement for cost-efficient, on-time delivery - Strong troubleshooting and research skills for electrical evaluation, testing, and design optimization 🔑𝐊𝐄𝐘𝐖𝐎𝐑𝐃𝐒: Embedded Design, Hardware Design, Firmware Development, Mobile App Integration, IoT Device, Medical Device Design, Embedded Systems, Real-time Operating Systems (RTOS), Microcontroller Programming, Sensor Integration, Wireless Communication (Bluetooth, Wi-Fi), Low Power Design, Wearable Devices, Firmware Architecture, Embedded Software, Device Drivers, System-on-Chip (SoC), PCB Design, Signal Processing, IoT Platforms, Cloud Integration, Mobile App Development, Web Portal Design, Healthcare Technology, Remote Monitoring, Data Security, Telemetry, ARM Cortex, ESP32, Device Connectivity, Embedded Prototyping, Human-Machine Interface (HMI), Medical Device Compliance, Mobile-Connected Devices, IoT Security, BLE, Firmware Debugging, Connectivity Solutions, Edge Computing, Smart Devices, Industrial IoT.

# 💼 Profile **Looking for a developer who can build modern web applications or high-converting Shopify stores?** I'm a **Front-End Developer & Shopify Expert** with **5+ years of professional experience** delivering scalable web applications and eCommerce solutions for startups, agencies, and international businesses. My expertise spans both **modern Front-End development** and **Shopify ecosystem**, allowing me to build everything from business websites and dashboards to custom Shopify themes and apps. I enjoy transforming complex requirements into clean, maintainable, and high-performance applications with an emphasis on user experience, scalability, and code quality. ### My expertise includes * Front-End Development with **React.js, Next.js, Vue.js, TypeScript, JavaScript** * Shopify Theme Development & Customization * Shopify App Development (Remix & Node.js) * Responsive UI Development from Figma/XD * API Integration (REST & GraphQL) * Performance Optimization * SEO & Core Web Vitals Optimization * Custom Components & Design Systems * E-commerce Development * Bug Fixing, Refactoring & Feature Development Whether you need a custom web application, a scalable front-end architecture, or a fully customized Shopify experience, I can help deliver clean, reliable, and production-ready solutions. I focus on: * Clean & maintainable code * Pixel-perfect implementation * Responsive UI across all devices * Performance optimization * SEO-friendly development * Reusable component architecture * Long-term scalability --- # 🧠 Technical Skills ### Front-End * React.js (5+ years) * Next.js (3+ years) * Vue.js (2+ years) * TypeScript * JavaScript (ES6+) * HTML5 * CSS3 / SCSS * Tailwind CSS * Redux Toolkit * Context API * React Query * Zustand ### Shopify * Shopify Liquid * Theme Development * Theme Customization * Shopify App Development * Remix * Node.js * Shopify APIs * Metaobjects * App Extensions ### Other Technologies * Node.js * Express.js * REST API * GraphQL * Git & GitHub * Vercel * Performance Optimization * SEO * Responsive Design --- # 🛠 Services ### Front-End Development ✅ React.js Development ✅ Next.js Development ✅ Vue.js Development ✅ TypeScript Development ✅ Responsive UI Implementation ✅ Dashboard & Admin Panel Development ✅ Landing Page Development ### Shopify Development ✅ Custom Shopify Store Development ✅ Theme Customization ✅ Shopify App Development ✅ Product Page Customization ✅ Shopify Performance Optimization ✅ Store Maintenance ### Additional Services ✅ API Integration ✅ Performance Optimization ✅ Bug Fixes & Refactoring ✅ Long-term Development Support --- ## 🌍 Selected Projects 🌍 **Selected Projects** ### Shopify & E-commerce * upfront.nl * theundone,com * fellaswim,com * international,fellaswim,com * reformebeauty,com * mercimaison,com * blushbees.us * espadasymas,com * autorrautomocion,com * 360haircare,com * youlockin,com ### Web Applications & CMS * lebanoninnovate,com * cms,lebanoninnovate,com * frodz.qa * smartrestoration,com ...and many more successful projects across Shopify, eCommerce, SaaS, CMS, and enterprise web applications. ...and many more custom web applications and eCommerce solutions.