Andrii Zelenets

Full-stack software engineer with 13+ years of production experience, specialising in Ruby on Rails backends and React frontends - with growing Node.js/NestJS depth in TypeScript-native projects.

Individual contributor, owning product feature delivery end to end - driving architecture decisions, mentoring juniors.

Recent projects

• As Product Engineer built TypeScript monorepo, NestJS CQRS backend with dual Socket.IO gateways for IoT device telemetry and live operator dashboards, NATS JetStream for guaranteed event delivery, BullMQ for background signal processing, and a React 18 + Vite frontend with Leaflet maps, D3.js telemetry charts, and JWT RBAC across three operator roles. Full test coverage: Jest (backend), Vitest (frontend), Playwright (E2E).
• As Full Stack Engineer contributed to a large Rails 7 monolith serving millions of investors. Extended APIs, optimised query strategies across a dual-database stack (MariaDB + PostgreSQL) with Elasticsearch and Sphinx search, maintained Redis caching and Resque background workers, and worked on multi-gateway subscription infrastructure (Stripe, Braintree, Zuora)
• As Product Engineer extended a mission-critical bioscience Rails e-commerce platform with real-time order tracking across 10+ ActionCable + Ably WebSocket channels, Sidekiq Pro job orchestration, and MongoDB data models. Delivered full-stack features across three SOX-compliant frontend surfaces using React/Redux and a shared Radix UI design system
• Led a team of four as Lead Solution Engineer, architecting a platform from scratch (Rails REST API, ActiveAdmin, Next.js marketing site, React customer app). Delivered OAuth integrations, multi-gateway payment pipelines (Stripe, PayPal, Apple/Android IAP), 83% test coverage,and 100% Swagger documentation. Result: +17% paid conversion, $5M in revenue

Dnipro Polytech, August 2009 - July 2012, Dnipro

Department: Automation & Computer Systems

Specialization: Computerized systems, control and automation

Qualification: Computer systems engineer, researcher. Master of Science in Mechatronics, Robotics, and System Automation Engineering (Diploma with Honor)

Thesis project: Directed movement of a tunnel boring machine along a laser beam + Photovoltaic matrix development, MatLab/MathCad model

Dnipro Polytechnical College, September 2005 - July 2009, Dnipro

Department: Production processes automation

Specialization: Automation, computer-integrated technologies and robotics

Qualification: Electromechanical technician for installation and commissioning of technological production automation equipment and systems

Thesis project: Automated control system for air heaters in steel production