Vitalii M.

Full-stack developer (with 10+ years of experience) for SaaS and MVP delivery with AI/LLM features (Node.js/NestJS, React/Next.js, TypeScript, PostgreSQL). 20,000+ users joined the waitlist for a product we built with our team. I’m a senior full-stack developer building B2B SaaS, multi-tenant products, marketplaces, internal tools, and AI-powered product features. As a full-stack developer, I design backend + frontend together so the platform stays clean, secure, and scalable from MVP → v1 → growth. 🤝 Working model (solo or team) You work with an engineer from our team on Upwork - no unnecessary bureaucracy. Need one full-stack developer - we’ll assign the best fit. Need a team - we’ll scale with the right people. 🧩 What I build as a full-stack developer (SaaS, MVP, B2B platforms) As a full-stack developer, I ship: * B2B SaaS platforms & multi-tenant products (subscriptions, RBAC, teams) * MVPs that can grow into v1 without rewrites * Marketplaces & booking platforms (catalog, vendors, inventory, payments, commissions) * Internal tools, admin dashboards, back-office systems * Customer/partner portals with role-based access * Data-heavy apps (workflows, forms, filtering, reporting) If you’re hiring a full-stack developer because this is a real platform (users + data + business logic), that’s exactly my lane. ⚙️ Full-stack developer coverage (backend, APIs, data, security) As a full-stack developer, I cover: * Architecture: modular monolith by default; microservices only when justified * APIs: REST, webhooks, clear contracts for frontend/partners * Integrations: Stripe/Stripe Connect, PayPal, CRMs, email, third-party APIs * Data: PostgreSQL/MySQL schemas, migrations, indexing, performance tuning * Security: JWT/sessions, RBAC/permissions, rate limiting, audit logs * Stabilisation: refactors, tests, regression reduction, reliability improvements You get a full-stack developer who can build new features and keep the codebase maintainable. 🤖 AI / LLM features (product-grade, not demos) As a full-stack developer, I implement AI features that actually fit into a SaaS product: * LLM integration (OpenAI or similar) for summarisation, extraction, classification, routing * Embeddings + RAG-style retrieval over docs/knowledge bases/internal data * AI assistants inside the product (support, onboarding, internal ops tools) * Prompt/version management + safe fallbacks (so the feature doesn’t break the product) If AI doesn’t add ROI, a good full-stack developer keeps the solution simple and stable. 🛠 Tech stack (focused) Frontend * React, Next.js, TypeScript, Tailwind / component systems Backend * Node.js, NestJS, Express Data * PostgreSQL, MySQL, MongoDB, Redis AI * LLM integrations, embeddings, RAG pipelines Delivery * Docker, CI/CD, AWS (EC2/ECS/RDS/S3) 🔄 How I work (SaaS/MVP delivery) Working with me as your full-stack developer: * Quick discovery (goals, users, constraints, integrations) * MVP scope → clear milestones → predictable releases * Clean code, docs, and stable handoff-ready setup * Long-term support and iteration after launch ✅ When we’re a good match * You need a full-stack developer for SaaS/MVP work (multi-week product delivery) * You want ownership across frontend + backend + integrations * You need AI/LLM features implemented like product features, not a hacky demo * You care about readable code and long-term maintainability Last updated: 31 May 2026