Олександр

Oleksandr Stelmashchuk
Backend Developer | Node.js / TypeScript
Ternopil, Ukraine​
[відкрити контакти](див. вище в блоці «контактна інформація»)​
Telegram: @OlexandrMS​
LinkedIn: [відкрити контакти](див. вище в блоці «контактна інформація»)​
GitHub: github.com/Lindexy

Summary
Backend Developer with 4 years of experience building REST APIs, backend services, crypto integrations, and
automation systems with Node.js and TypeScript. Worked on trading platforms, blockchain transaction flows,
data automation, and high-load backtesting solutions using NestJS, PostgreSQL, MongoDB, and AWS.

Skills
Languages: JavaScript, TypeScript, SQL​
Backend: Node.js, Express.js, NestJS, REST APIs​
Frontend: React, Next.js, basic UI implementation​
Databases: PostgreSQL, MongoDB, Prisma, Sequelize, Mongoose​
Infrastructure & Tools: AWS, Linux, Git​
Blockchain & Automation: Ethers.js, Puppeteer, WebSockets, SSE​
AI-assisted development: Claude code, Codex, code review, debugging, refactoring, documentation

Experience
Backend Developer​
Commercial projects | 2022 – Present

●​ Built backend services, REST APIs, and automation tools using Node.js and TypeScript
●​ Delivered production features for crypto, logistics, education, and trading-related products
●​ Worked across backend architecture, integrations, database design, and real-time systems

Projects
Crypto Trading Bot

●​ Built and shipped a crypto trading platform end-to-end, from architecture to deployment
●​ Implemented a live Binance Futures trading engine with WebSocket market feeds, strategy-based
entries and exits, and risk controls including stop-loss, take-profit, breakeven, and leverage
●​ Developed a walk-forward backtesting and strategy optimization module with technical indicators and
parallelized computations using worker threads
●​ Designed REST APIs and product features for trader lifecycle management, JWT authentication, user
settings, and test/log result tracking​
Stack: TypeScript, Node.js, Express, Prisma, PostgreSQL, WebSockets

Dino Wars (Blockchain Game Backend)
 ●​ Designed and built a Node.js/Express backend from scratch, including architecture,
PostgreSQL/Sequelize data model, and REST APIs
●​ Implemented secure user and wallet lifecycle features, including account creation, mnemonic
encryption, JWT authentication, refresh tokens, and email one-time login tokens
●​ Delivered blockchain finance logic on BNB Chain with ethers.js, including balances, transfers, token
swaps, staking, vesting, and external payouts
●​ Shipped a versioned game-facing API and financial operation history/status tracking for auditability​
Stack: Node.js, Express, PostgreSQL, Sequelize, Ethers.js, BNB Chain

DL2 — Freight Automation Platform

●​ Built and shipped a full-stack TypeScript product from architecture to production
●​ Automated multi-page freight data scraping with deduplication, status tracking, and scheduled runs
●​ Implemented resilient external API synchronization with queueing, rate limiting, retries, and failure
recovery
●​ Delivered a real-time operations dashboard with SSE, React Query, live card updates, filtering, and
decision workflows​
Stack: TypeScript, NestJS, React, PostgreSQL, SSE

Fire Safety Training & Compliance Platform

●​ Built core backend and product functionality for a training platform using TypeScript, Prisma, and
PostgreSQL
●​ Implemented OTP authentication, lesson progress tracking, exam workflows, and certificate issuance
with expiration logic
●​ Developed PDF certificate generation, public verification pages, and payment integration with signed
webhook validation and idempotent processing
●​ Supported multilingual content delivery across 3 courses and 48 lessons​
Stack: Next.js, TypeScript, Prisma, PostgreSQL

Education
Master’s Degree in Economics​
National University of Life and Environmental Sciences of Ukraine, 2018

Languages
English: English — B1/B2 (Intermediate)​
Ukrainian: Native