TOMOYUKI Y.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 Jul 17, 2026.

👋 Hey — I’m Tomoyuki Full-Stack & AI Engineer 🌐🤖 Building scalable SaaS platforms, AI systems, and production-grade infrastructure 🧠 What I Do I specialize in AI-powered SaaS and full-stack development, combining modern web technologies with real-world AI systems. 📊 Core Stack - TypeScript, Next.js, React, Node.js, NestJs, Vue.js - Python (FastAPI), Django, AI pipelines, automation - PostgreSQL, MongoDB, Vector DBs (FAISS, Chroma) - AWS / GCP / Azure - Docker, CI/CD, scalable infrastructure ⚙️ My Approach: Ownership-Driven Engineering I work as an independent engineer, not just a developer. I take full responsibility for architecture, scalability, and long-term maintainability. ✨ How I collaborate best - Clear goals → I design & execute - Async-first → Deep focus, minimal meetings - Direct communication → Honest technical feedback 🚀 What I Bring * 💡 AI-First Systems - RAG systems (Graph RAG, hybrid search) - LLM integrations (OpenAI, local models) - AI automation & multi-agent workflows * 🏗️ SaaS Platform Expertise - Multi-tenant architecture design - Subscription & billing systems - Scalable backend + API design - Performance optimization & cost control *🔍 Pragmatic Engineering - Performance over hype - Maintainability over shortcuts - Cost-efficiency from day one *🧩 Ownership Mindset I build systems as if I’ll maintain them long-term. 🧱 What I Build - AI SaaS Platforms End-to-end SaaS products with AI features (chat, automation, analytics) - Full-Stack Applications Scalable web apps, dashboards, admin panels - RAG & Data Systems Large-scale document processing, semantic search, knowledge systems - APIs & Integrations Payment systems (e.g. Shopify, GMO Payment Gateway), third-party services - Automation & Internal Tools Workflow automation, business process systems 🤝 How I Work - Independent Contractor (Freelance) - Remote & async-first collaboration - Outcome-driven (focused on results, not hours) 🌱 Why Work With Me - I think beyond code → *product & SaaS architecture* - I provide *honest, senior-level technical insigh* - I deliver *fast, scalable, and maintainable solutions* Japan-Based · Globally Available (Flexible Across Time Zones) Tomoyuki — Full-Stack & AI Engineer