Олександр

Oleksandr Sterenchuk
Backend Developer
Vienna, Austria · [open contact info](look above in the "contact info" section) · [open contact info](look above in the "contact info" section) · github.com/Sterenchuk · [open contact info](look above in the "contact info" section)
Backend Developer with hands-on experience across an internship, a startup, and independent freelance work, building production NestJS APIs on PostgreSQL, MongoDB, and Redis. Ships complete backend features — authentication, authorization, real-time services, third-party API integration, and security-hardened data flows — and runs self-hosted Linux production infrastructure with Docker, Nginx, and Traefik. Comfortable owning a feature from schema design through deployment and monitoring.
KEY BACKEND PROJECTS
Secure Voting & Survey Platform
NestJS · PostgreSQL · MongoDB · Redis · WebSockets · Docker · Nginx · Traefik
• Designed a NestJS backend with polyglot persistence — PostgreSQL for relational data, MongoDB for an append-only audit chain, Redis for atomic sequencing and caching — architected to EU CM/Rec(2017)5 compliance standards
• Built strict voter anonymity into the schema: no foreign key links participation records to ballots; ballots authenticated via HMAC-SHA256 receipts instead of user identity
• Implemented JWT authentication, RBAC authorization, a two-step email-confirmation voting protocol, real-time WebSocket result broadcasting, and OASIS EML 510 XML export
• Load-tested the API to 5,000 req/s with k6 and self-hosted the full stack via Docker Compose, Nginx, Traefik v3, and Cloudflare Tunnel
Online Shop (E-Commerce Backend)
NestJS · PostgreSQL · Prisma · Redis · Docker · Nginx
• Built a NestJS REST API covering authentication, product catalog, cart, and order management with JWT and RBAC end-to-end
• Modeled the schema with Prisma ORM, added Redis session caching, validation pipes, and structured error handling
• Deployed via Docker Compose, Nginx, and Cloudflare Tunnel for self-hosted production hosting
EXPERIENCE
Backend Developer Intern — OnixNov 2025 – May 2026
• Delivered backend features in a production NestJS codebase over a 7-month internship, building REST API endpoints and contributing to PostgreSQL schema design
• Worked with Docker-based deployment and CI processes in a live production environment
• Participated in code review, Git workflow, and Agile ceremonies; collaborated cross-team with senior engineers on delivery estimates and technical decisions
Backend Contributor (API Integration) — AI Automation Solutions Startup2025
• Contributed backend work to an early-stage startup building AI-driven automation workflows
• Implemented and tested API request handling to connect automation pipelines with third-party services, including error handling and response parsing
• Worked directly with the founding team in a fast-moving, ownership-heavy environment typical of an early startup
IT Teacher — Inter-web IT SchoolFeb 2024 – May 2025
• Taught HTML, CSS, JavaScript, and full-stack architecture fundamentals to beginners; mentored debugging workflows and client-server concepts
Freelance Backend Developer — Independent — Small Business Clients2024
• Built a website for a local building-materials business on Express.js, owning backend/server logic while collaborating with a friend on the frontend
• Delivered small, essentials-first solutions scoped to real client budgets and timelines — catalog display, contact/inquiry flow, basic content management
Project Coordinator — UNICEF UPSHIFT Program2023
• Coordinated a youth career-guidance project end-to-end — logistics, budgeting, and stakeholder communication with psychologists and career consultants
• Built the program's first Telegram bot for participant outreach
EDUCATION
BSc Computer Science — Central Ukrainian State University
2022 – 2026 (Graduated)
• Avg 96/100 · Group Starosta · Diploma Thesis: Secure Electronic Voting System
• DILLUGIS 24 – Project Management & Agile · Germany · 5 ECTS · 93/100
• Participant, university-level programming competitions
• Co-author, academic journal publication (in progress)
TECHNICAL SKILLS
• Backend: NestJS · Express.js · REST · GraphQL · WebSockets
• Databases: PostgreSQL · MongoDB · Redis · Prisma · Mongoose
• Auth & Security: JWT · HMAC-SHA256 · RBAC · OAuth2
• DevOps: Docker · Docker Compose · Nginx · Traefik v3 · Cloudflare Tunnel · Linux (Ubuntu 24.04) · Git
• Languages: TypeScript · JavaScript · Python (basic)
• Frontend (supporting): Next.js · React · Tailwind CSS
CERTIFICATIONS & AWARDS
• Cisco – Ethical Hacker
• Cisco – Networking with Packet Tracer
• Cisco – IoT Fundamentals
• IELTS Academic C1 (2026)
• KPI Hackathon – 3rd Place (Catnip Coders)
• TechForAll Hackathon – 3rd Place (2025)