Khanh D.Private profile: Upwork shows its earnings only to signed-in members, so we check it every few weeks, not daily. MRR here is a rough estimate (Upwork's six-month earnings ÷ months active). Last read Sep 25, 2026.

💻 Long-term work for growing products - Java/Kotlin/Typescript Full Stack with 7+ years of working with international clients (US, Israel, Luxembourg, Kuwait...) across domains like eCommerce, payroll systems, adTech platforms, and enterprise web integrations. 🧠 Domain Expertise: - 🛒 eCommerce: Product catalogs, checkout flows, Stripe/PayPal, inventory sync - 🧾 Payroll Systems: Role-based dashboards, payroll calculation logic, secure HR workflows - 📊 AdTech: Campaign builders, analytics dashboards, API integrations - 🌐 Web Integration: 3rd-party API services (Twilio, Firebase, Google APIs), legacy system migration 🔧 Tech Stack: ✅ Backend: Java (11–25), Spring Boot 2 & 3, Quarkus, NestJS, Microservices, REST APIs, Firebase ✅ Frontend: Angular, Vue.js, React.js, HTMLX, TypeScript, JavaScript, GUI/UX-focused UI ✅ Databases: MySQL, PostgreSQL, MongoDB, Liquibase, Flyway ✅ Security & Scalability: OAuth2, KeyCloak, SonarQube, Load optimization (100K+ daily requests) ✅ DevOps: Docker, GitHub Actions, CI/CD pipelines ✅ Third-party Integration: Stripe, PayPal, Myfatoorah, Google APIs, Firebase API, Algolia Search, Twilio, Telnyx, Recaptcha,... 🌍 **International Collaboration** - Experience working across different time zones and work cultures - Strong English communication and proactive project ownership 🎯 Why clients work with me: - Fast onboarding & clean code - 100% Job Success | Trusted by long-term international clients - End-to-end delivery: Dev → Test → Deploy 📩 Let’s connect — I’d love to hear about your project!