Roy K.

Senior Web & Mobile developer with experience at top US and German companies, available for long-term, design conversion, and high-impact/complex projects. I am also skilled in AI-assisted development with Claude & Codex. My Industry experience spans across Fintech, Healthtech startups, Dev shops, and YC startups. EXPERIENCE: Upwork (U.S. Fintech): Recently completed a major modernization project for a U.S. fintech platform, helping migrate business-critical systems from legacy JSP to modern Angular 21 in approximately four months. Alongside feature development, I worked on multiple financial modules, integrations, authentication, onboarding, and platform workflows. Kinnect-US - (U.S SAAS Startup): Led a team of global developers in a major refactoring process that resulted in 60%+ code reduction, Application performance improvements, and optimisation. Clean code reviews and readability, which helped the company raise valuations and Series A and B. Sanical - (German HealthTech Startup): Lead Frontend Engineer: I built the company's mobile app that helps clients interact with therapists on the Go. Also built the web dashboards for monitoring data and therapist dashboards for setting profiles, scheduling, video conferencing, chat, payment withdrawal, journaling, and more. Diligent Systems - SaaS / Social Platform: I helped architect a reusable design system and style guide for a social platform, while working on high-performance interfaces, API integrations, accessibility, code reviews, and frontend architecture. TagDev Technologies - Multi-Product Development(Dev Shop): Working in a development environment with clients across different industries taught me to become highly adaptable. I worked across React, Next.js, Redux, Vue, and Angular, building products including monitoring dashboards, logistics applications, e-commerce systems, and data-driven platforms. One example was a real-time logistics tracking system using React, WebSockets, and Google Maps, allowing operations teams to monitor delivery riders and activity in real time. I’ve also built AI-powered experiences, including a search engine combining OpenAI with Google Maps to help users discover greener cities. Core Technical Strengths Claude & Codex (AI-assisted development) Angular | Next.js (modern architecture, RxJS, NgRx) MongoDB, PostgreSQL TypeScript, JavaScript, HTML, SCSS, Tailwind REST APIs, Node.js collaboration Google Maps, real-time data systems Enterprise UI systems and scalable component design How I Work With Clients I don’t just “implement tasks”. I think like a product engineer. • Clean architecture, not hardcoded hacks • Performance-first mindset • Clear communication and ownership • Ability to integrate into complex existing systems • Focus on long-term maintainability, not quick fixes If your project is complex, data-driven, or performance-critical, I’m the kind of engineer you want on it.