Hire the Best Android Developers
in Vietnam

Over the span of 13 years, I've immersed myself in the realm of native Android application development, culminating in a diverse portfolio that encompasses an array of dynamic projects. This includes the creation of highly secure and encrypted communication platforms (OTTs), innovative social networks, robust cryptocurrency exchanges, efficient system utilities, intuitive online stores, intelligent smart assistants, and a wide spectrum of other application categories. At the core of my skill set is the art of crafting resilient and high-performance Android applications that seamlessly traverse the landscape of various devices – from smartphones to tablets – all while optimizing CPU and memory resources. My expertise extends beyond coding; I possess extensive experience in architecting efficient team workflows, along with a keen eye for conducting meticulous code reviews, ensuring the delivery of exceptional projects. My hands-on proficiency involves constructing formidable codebases using the MVP/MVVM architecture, employing languages such as Java and Kotlin, and harnessing the power of Gradle. This proficiency is underscored by a deep-seated understanding of essential object-oriented programming concepts, a rich repertoire of software design patterns (including Singleton, Observer, Factory, and Decorator), comprehensive testing methodologies (spanning Unit, Integration, and Automated UI tests), and a spectrum of cutting-edge technologies that have been embraced by the Android development community. As I embrace new horizons, I am actively seeking opportunities not only to engineer and deliver top-tier applications but also to offer innovative solutions that can fuel the growth of your business. I invite you to connect with me, and let's collaboratively shape the trajectory of your applications and business endeavors.

I am a mobile app developer focused on building production ready applications using 𝙍𝙚𝙖𝙘𝙩 𝙉𝙖𝙩𝙞𝙫𝙚 and 𝙁𝙡𝙪𝙩𝙩𝙚𝙧. I specialize in 𝙁𝙞𝙣𝙩𝙚𝙘𝙝 and 𝙇𝙤𝙜𝙞𝙨𝙩𝙞𝙘𝙨 apps where reliability, real time data, and system stability are critical. I have worked on mobile products that go beyond UI development and deal with real world complexity such as payment flows, live tracking systems, offline usage, background sync, and performance optimization under unstable network conditions. My goal is to build mobile apps that are stable, scalable, and ready for real users from day one. I mainly work with clients from the United States, United Kingdom, Canada, and Australia. I can easily align with your timezone to ensure smooth communication and fast iteration during development. 🏦 Fintech Applications I build mobile finance systems that require accuracy, security, and consistency. Challenges I solve include 🔻 Preventing duplicate transactions in unstable network conditions 🔻 Building real time wallet and balance updates without UI issues 🔻 Integrating Stripe and payment systems with backend reconciliation 🔻 Secure authentication and role based access flows 🔻 Designing simple dashboards for complex financial data The result is stable fintech applications that handle sensitive operations with confidence. 🚚 Logistics and Mobility Applications I build apps focused on real time tracking, movement, and operational workflows. Challenges I solve include 🔻 Live GPS tracking with optimized battery usage 🔻 Real time driver and delivery status synchronization 🔻 Offline functionality for low connectivity environments 🔻 Map performance optimization using Google Maps SDK 🔻 Background location tracking without crashes or delays The result is reliable logistics systems used in real operational environments. ⚙️ Tech Stack ∘ React Native ∘ Flutter ∘ Node.js ∘ Express ∘ FastAPI ∘ Firebase Authentication ∘ Firestore ∘ Cloud Messaging ∘ Supabase PostgreSQL ∘ Supabase Edge Functions ∘ Stripe Payments ∘ Google Maps SDK ∘ REST APIs ∘ GraphQL APIs ∘ Git and CI CD ∘ App Store and Play Store deployment 🧠 How I Work Most mobile apps fail because of poor data flow, unstable backend integration, or missing edge case handling. My approach focuses on Designing data flow before UI Building strong API integration structure Handling offline and failure cases early Optimizing performance during development, not after launch Ensuring stable user experience under real usage conditions 🌍 Clients I Work With I work with startups and businesses building serious mobile products, especially in fintech and logistics domains. Most of my clients are based in - United States - United Kingdom - Canada - Australia - Germany ⏰ Timezone I can align with your timezone to ensure smooth communication, quick feedback cycles, and efficient collaboration throughout the project. 🚀 What You Get - Production ready mobile applications - Clean and scalable architecture - Strong performance and reliability focus - Fast and clear communication - Long term maintainable codebase 💪 Interested in working together? Feel free to click the Message button. Let’s discuss your project goals and see how I can help you build a reliable and scalable solution. 🔎 Upwork SEO Keywords mobile app developer, React Native developer, Flutter developer, fintech app developer, logistics app developer, GPS tracking app developer, real time mobile app, Firebase developer, Supabase developer, Node.js backend developer, cross platform mobile apps, iOS Android developer, Stripe integration, payment app developer, mobile app architecture, offline first mobile app, Google Maps integration, fleet management app, delivery tracking app, mobile API integration, scalable mobile apps, push notifications Firebase Cloud Messaging, backend integration mobile apps

Hello! My name is Hoang, I am a Top Rated Mobile developer with 100% Client Satisfaction on Upwork. My Upwork profile is a testament to my ability to deliver products of excellent quality, punctually and without any hassle. For me, prioritizing client satisfaction is paramount. 🎯Why you should hire me? ✅Best price with hight-quality work ✅Dedicated to the job process ✅Client satisfaction ✅Quick response ✅Alway available for new updates and maintaining/bug fixes. 🎯 Areas of Expertise: ◉ Native Mobile App Development: Swift, Objective-C, Kotlin, Java ◉ Cross-platform with React Native ◉ AI, Chatbot, SDK, Livestreaming, Social networking ◉ API Integration: AWS API Gateway, AWS Lambda, Rest API, JSON, XML, PHP, Node.js, Python ◉ Database: SQLite, MySQL, Parse, MongoDB, AWS DynmoDB, Firebase real-time DB ◉ Social Integration: Facebook, Twitter, Youtube, Instagram, Snapchat, Tinder ◉ Chat Video/Photo/Text: XMPP, Socket, Firebase, Twilio ◉ Payment Gateway: Paypal, Braintree, Stripe, Paywall, RevenueCat, AppHud ◉ In-app Features: In-App Purchase: Advertisement, Push Notifications, GCM, Google Analytics ◉ Version Control Tools: Github, Bitbucket, Gitlab ◉ Google Map, Apple Map kit, Geolocation, GPS, Location Tracking 💌 Please, feel free to send the invitation to your job post or message me. I'm always looking forward to engaging opportunities!

✅ 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

I have 8 years of experience as a skilled Android and Flutter developer. My passion lies in creating visually appealing and intuitive mobile applications with the Flutter framework. I am well-versed in Flutter's architecture and ecosystem, which enables me to deliver high-quality and robust applications that meet clients' requirements. Here are some of my skills: 👉 Flutter: Extensive experience in developing cross-platform mobile applications using the Flutter framework. Proficient in building interactive UIs, implementing complex animations, and managing state within Flutter applications. 👉 GraphQL: Hands-on experience in building GraphQL APIs and integrating them into Flutter applications. Can design and implement GraphQL schemas, resolve queries and mutations, and establish real-time communication using GraphQL subscriptions. 👉 Socket Programming: Expertise in socket programming and developing real-time applications using libraries such as Socket.io and WebSockets. Capable of implementing bidirectional communication channels, handling event-based messaging, and ensuring data synchronization between clients and servers. 👉 NFC (Near Field Communication): Worked with NFC technology to enable communication between devices and NFC-enabled tags or cards. Developed applications that read and write NFC tags, handled NFC transactions, and integrated NFC functionality into Flutter applications. 👉 Restful APIs: Strong understanding of RESTful API principles and experience in implementing APIs using frameworks such as Express.js and Django. Can design API endpoints, handle authentication and authorization, and process data in JSON format. 👉 Git: Proficient in version control using Git, including creating branches, merging code, resolving conflicts, and maintaining a clean commit history.

Build fullstack applications and AI-powered backends. 6+ years of shipping products, mostly with Kotlin (Android native) and Flutter, plus Python and Node.js on the backend. AWS Certified ML Engineer. Most of my work follows the same pattern: take an idea or spec, build the mobile app, wire up the backend, ship it. I've done this for crypto exchanges, e-commerce platforms (one had a 3D virtual try-on feature using Unity), social apps, and more recently AI products - a transcription app using self-hosted speech-to-text, an AI trading platform with LLM-driven backtesting, and an AI keyboard with on-device Gemma Nano. On the AI side, I work with LangChain, LangGraph, and RAG pipelines. I've built MCP servers that bridge LLMs with external APIs, deployed models with vLLM, and integrated Gemini into production apps. Not the "I watched a tutorial" kind of experience - I architect these systems end to end and put them in front of real users. Mobile is my core: - Kotlin + Jetpack Compose / Android Native, 6 years, 15+ shipped apps - Flutter + Dart cross-platform, 6 years - Clean Architecture, MVVM/MVI/BLoC - Blockchain wallets, NFT marketplaces (Ethereum, Polygon, BNB) Backend and AI: - Python (FastAPI, Django), Node.js, Go, Java - LangChain, LangGraph, LlamaIndex, RAG, vLLM, Gemini, Google ADK - MCP server development (Python, TypeScript, C#) - AWS (Lambda, SageMaker, ECS, API Gateway), Docker, CI/CD I've led teams up to 24 people and also shipped projects with 2-person teams. Both work fine - I adjust to what the project needs. If you need someone who can handle both the mobile frontend and the AI/backend plumbing, let's talk specifics.