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Hello! I’m Senior developer with over 10 years of professional experience building enterprise-grade applications, RESTful microservices, and cloud-native solutions. I have successfully delivered projects for clients across Europe, the UK, Australia, India, South Africa, and the USA. ✅ Languages: Java, Kotlin, Groovy, Python, Node.js, Rails, TypeScript ✅ Ai: Agentic Ai, Subagent, Harness, Hermes Agent, SDD, TMUX, RAG, GraphRAG, Voice Ai Agent, Elevenlabs, n8n, FlowiseAI ✅ Back-End: Spring Boot, Spring Cloud, Spring Security, Micronaut, Camel, Express.js, NestJs ✅ Front-End: Angular, Vue.js, Nuxt, HTMX, Django, Tailwind CSS, Bootstrap ✅ Databases: PostgreSQL, MySQL, Oracle, MongoDB, Redis, Neo4J, DynamoDB ✅ Cloud & DevOps: AWS, CDK, Cloudformation, ECS, API Gateway, Lambda, Cognito, DynamoDB, Azure, Docker, Kubernetes, Terraform, Jenkins, GitHub Actions, Cloudflare ✅ Architecture: Clean Architecture, Hexagonal, Domain-Driven Design DDD, Microservices, Monolith ✅ Messaging: Kafka, RabbitMQ, ActiveMQ, Artemis ✅ Monitoring: Grafana, Kibana, Datadog ✅ APIs: REST, SOAP, gRPC, GraphQL, Websocket, SSE, tPRC ✅ Build & Tooling: Maven, Gradle, Flyway, Liquibase ✅ Opensource contribution to popular opensource projects like FlowiseAi, AWS PDK, Mongock, Jhipster lite and Jhipster Main generator. You can confidently entrust me with your project and you will not be let down by our collaboration. I assure you of my strong sense of responsibility and the high standard of the work I deliver, which you can rely on once I become part of your team.

✅ 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

Android, iOS, Java, .Net Development experts with extensive knowledge of US Healthcare software development and integration. Technosoft is an ISO 9001:2008 certified, IBM Advanced Business Partner, MySQL Partner & CMMI ML2 appraised, company. Healthcare Expertise Include: - HL7, FHIR, C-CDA, CCD, HIPAA, EMR, EHR, m-health, SMART on FHIR, CDS Hooks, cTakes - EPIC, Cerner, AllScripts, Kareo, Athena, Open Dental, HBOC, Siemens, Quest, EHR integration - Custom Interface, Medical Billing, Scheduling, Laboratory Integration, Athena Integration, Kareo, Redox integration Technical Expertise includes: - Python, Django, Celery Beat, Flask - iOS (Objective-C, Swift, Siri, BLE, etc) - Android - Front End Development (JQuery, Ajax, Node.js, AngularJS, ReactJS - Java/J2EE (Spring, Hibernate, JSF, Play framework, Spring Boot, Scala, etc) - .Net ASP.net, VB.net, C#, WPF, WCF, SignalR, Web Forms, Azure - Wearable Devices integration (Misfit, Fitbit, Mi-Band, etc) - Alexa/Alexa Show Skills Development - DiagFlow, Lex, Twilio, NLU, NLP, Siri, and other voice integration technologies. I am a HIMSS Certified Healthcare Security Professional and run my company Technosoft solution. We focus solely on the US healthcare market and are very well versed in HIPAA, HL7, FHIR, SMART on FHIR and other healthcare standards. We have developed video conferencing (WebRTC), EMR, prescriptions, lab orders, lab results, billing, EDI and other Healthcare Information Systems modules. We are also very well versed in fitness, wearable and biometrics devices integration. Summary: - 14+ years Healthcare IT expertise - Software solutions deployed In over one thousand US hospitals/clinics - Strong Exposure to mHealth, webRTC, HIPAA, HL7, FHIR - SEI CMMI Level 2 Appraised - Excellent Communication Skills with hundreds of completed projects. - Experts in iOS, Android, Java/J2EE, .Net, Azure development - Experienced in Agile development with Daily/Weekly SCRUM via Skype or phone availability as per your Timing. - Daily/weekly status report - References available upon request. ✅ Top-Rated - Mobile Application (iOS, iPhone, Android) Developers ✅ Top Rated - Web Application (ASP.net, Java, J2EE) Developers ✅ 5 Star Feedback ✅ 100% Job Success Score ✅ Healthcare Software Experts ✅ With Elance/Upwrok for over 17 years ✅ 10,000+ Hours clocked on Upwork with 100% Client Satisfaction

I'm Huanqing Zhu, and you can call me Fusion. With over 10 years of hands-on Java development experience—including 6 years dedicated to big data processing and visualization—I’ve built my expertise by staying rooted in frontline coding, even as my responsibilities have grown. A key pillar of my technical toolkit is ‌6 years of production-grade Rust development experience‌, complemented by proficiency in Java, Scala, JavaScript, HTML5, and a full stack of big data and cloud-native technologies: Apache Spark, Hadoop, Hive, Flume, HBase, Storm, Kafka, DataX, ECharts, Docker, Kubernetes, and Linux. What sets me apart is that I’ve never stepped away from writing production code, even as I’ve taken on leadership and architectural roles: As a ‌hands-on Big Data Developer‌, I’ve built robust data ingestion utilities (including the open-source DataXServer on GitHub) and real-time page click analytics systems, directly coding pipelines to pull data from RDBMS, NoSQL databases, and file storage into production environments. As a ‌Big Data Architect‌, I’ve led platform design while still contributing core code, using Hadoop, Spark, Flink, and ElasticSearch to build scalable data infrastructure—no abstract planning here; I’ve written the critical components that power these systems. As a ‌Rust Specialist‌, my 6 years of experience spans building high-performance, low-latency systems. I’ve used Rust to optimize data processing pipelines, cut latency by up to 40% in high-throughput scenarios, and deliver systems that run 24/7 with zero critical errors. As a ‌Team Leader‌, I’ve managed full-stack teams (Java, front-end, QA, operations) while still pairing with developers on complex code reviews and contributing to high-priority features, ensuring I stay connected to the day-to-day challenges of software delivery. I also bring deep experience in microservices architecture and cloud-native containerization, and my cross-language expertise lets me bridge gaps between Java-based enterprise systems and Rust-powered high-performance components. If you’re looking for a professional who combines strategic vision with the grit to deliver production-ready code—someone who can architect a system, and write the Rust or Java code that makes it run—I’m the candidate for you. Thank you for reviewing my profile. I’m eager to discuss how my hands-on experience can add value to your team.

As a Backend Engineer with 3+ years of experience, I specialize in building scalable, secure, and high-performance applications using Java Spring Boot and Node.js. Recently, I’ve been part of a major project for the Egyptian government, developing a Correspondence Management System with advanced AI features for document processing and natural language database queries. Why Choose Me? - Robust APIs & Microservices – I build RESTful APIs and event-driven microservices with Spring Boot, Express.js, Kafka, and Redis. - Optimized Databases – I design and tune schemas in PostgreSQL, MySQL, MongoDB, and Elasticsearch for maximum efficiency. - AI-Powered Features – Integrated OCR (OCRmyPDF, Tesseract) and Chatbot with Text-to-SQL, making document handling and database access smarter and faster. - Real-Time Systems – Deliver chat, notifications, and live updates using Kafka, WebSockets, and Redis. - Cloud & Deployment – Deploy secure, containerized applications with Docker, Nginx, and platforms like AWS and DigitalOcean. - Secure Authentication – Implement JWT, Keycloak, and Spring Security for robust authentication and authorization. Key Highlights - Government Correspondence Management System (Spring Boot + AI): Integrated OCR and chatbot features for automated document processing and text-to-SQL database querying. - Social Network Platform (Spring Boot, Kafka, PostgreSQL): Posts, comments, likes, and multimedia sharing. - Search Engine (Spring Boot, Kafka, Elasticsearch): Fuzzy search and suggestion system. - Real-Time Chat App (MERN + Socketio): Private and group messaging with instant notifications. - Multi-Author Blog (MERN): Role-based publishing and content management. Services I Offer - Backend API Development (Spring Boot, Nodejs, Expressjs) - AI Integration (OCR, Chatbots, Text-to-SQL) - Microservices Architecture & Deployment (Docker, Kubernetes) - Database Design & Optimization (SQL & NoSQL) - Real-Time Communication Systems (Kafka, WebSockets, Redis) - Secure Authentication & Authorization (JWT, Keycloak, Spring Security) - Cloud Deployment (AWS, DigitalOcean, Docker, Nginx) Why Clients Trust Me - I deliver clean, tested, and production-ready solutions. - I apply OOP, SOLID principles, and software architecture best practices. - I communicate clearly, meet deadlines, and focus on results that matter. Let’s Collaborate! Whether you need to launch an MVP, scale a backend system, or integrate AI-powered features into your product, I can help you design backend solutions that are reliable, secure, and ready for growth.

**Java ☕, JavaScript 📜, Node.js 🔧, React ⚛️, API 🌐, PHP 💻, PostgreSQL 🐘, API Integration 🔗, Web Development 🕸️, MySQL 📊, SQL 📈, Web Application 🕸️, MongoDB 🍃, RESTful API 🔄, Amazon Web Services ☁️, HTML5 🖥️, TypeScript 📘, Next.js 🚀, CSS 🎨, AI Agent Development 🤖, Full-Stack Development 🛠️** My name is Khawaja Hamdan Ahmad, and I have 5 years of experience in full-stack development. Over this period, I have successfully completed over 60 projects, showcasing my ability to meet and exceed client expectations. I specialize in combining front-end and back-end development skills to create robust and scalable web applications. My expertise includes working with various databases, APIs, and modern web technologies to deliver top-notch solutions. How-To,DIY & Expert Content Leveraging my deep understanding of RESTful APIs and cloud services, I aim to drive innovation and efficiency in all projects. Your next big software solution is just a click away; let’s create something extraordinary together! **Java ☕** Proficient in object-oriented programming, developing versatile applications using Java. **JavaScript 📜** Creating dynamic web pages and interactive websites through robust JavaScript coding. **Node.js 🔧** Building scalable server-side applications with efficient runtime environments. **React ⚛️** Developing responsive user interfaces with component-based architecture. *API 🌐** Expertise in designing and integrating APIs for seamless data exchange. **PHP 💻** Developing dynamic and data-driven web experiences with PHP scripting. **PostgreSQL 🐘** Handling complex queries and managing data efficiently in PostgreSQL databases. **API Integration 🔗** Seamlessly connecting different software applications via leading-edge API integration. **Web Development 🕸️** Crafting comprehensive web solutions using modern technologies and methodologies. **MySQL 📊** Ensuring secure data storage and retrieval through well-structured MySQL databases. **SQL 📈** Mastery in SQL for managing and querying relational databases effectively. **Web Application 🕸️** Developing full-featured web applications from concept through deployment. **MongoDB 🍃** Utilizing MongoDB for flexible and scalable NoSQL data storage solutions. **RESTful API 🔄** Designing and implementing efficient RESTful services and endpoints. **Amazon Web Services ☁️** Leveraging AWS offerings for robust and scalable cloud solutions. **HTML5 🖥️** Building modern, responsive web designs with the latest HTML5 standards. **TypeScript 📘** Using TypeScript for superior code quality in JavaScript-based development. **Next.js 🚀** Developing server-rendered React applications for high-performance web solutions. **CSS 🎨** Styling responsive and visually appealing websites with CSS3 techniques **AI Agent Development 🤖** Engineering intelligent agents to automate complex tasks and workflows. **Full-Stack Development 🛠️** Expert in both front-end and back-end technologies for complete web solutions. Ready to bring your ideas to life? Contact me today, and let’s start building your next project!