Олег

OPEN TO BACKEND ROLES

Oleh Voloshyn
Backend Developer · Node.js / TypeScript
OV

oleh@cv:~$ email [открыть контакты](см. выше в блоке «контактная информация») tel [открыть контакты](см. выше в блоке «контактная информация») git github.com/Sledgeee

in [открыть контакты](см. выше в блоке «контактная информация»)

// summary Professional Summary

Backend Developer with 5+ years of commercial experience building scalable REST APIs, e-commerce platforms and SaaS systems. Strong
expertise in Node.js, TypeScript, PostgreSQL and distributed systems. Experienced in payment integrations, webhook-driven architecture,
caching strategies and microservices, with a focus on clean architecture, performance optimization and production-ready solutions.

// stack Tech Stack

LANGUAGES TypeScript JavaScript

BACKEND Node.js NestJS Express.js

DATABASES PostgreSQL Redis MongoDB

MESSAGING RabbitMQ

DEVOPS Docker NGINX

PATTERNS REST API Microservices Webhooks Payment Integrations Caching JWT WebSockets Audit Trails

// experience Experience

Backend Developer · Freelance / Contract 2021 — Present

Designed and developed scalable REST APIs using NestJS and Express.
Integrated payment systems (Stripe, LiqPay) including webhook-based billing logic and transaction handling.
Designed relational database schemas and optimized complex PostgreSQL queries.
Implemented Redis caching strategies to improve performance and reduce database load.
Developed SRM/CRM systems (under NDA) with role-based access control and reporting modules.
Built asynchronous processing flows using RabbitMQ.
Configured Dockerized environments and an NGINX reverse proxy for production deployments.

// projects Selected Projects

SmartSelect & LuminaLight E-COMMERCE

Designed backend architecture for large-scale e-commerce stores using NestJS.
Integrated LiqPay and Stripe for secure online payments.
Implemented product catalog management, filtering and pagination.
Built secure admin panels for order and inventory management with JWT auth and role management.

NestJS Stripe LiqPay PostgreSQL JWT

Moneywave & Finance CRM FINTECH

Built real-time data updates using WebSockets.
Developed transaction and balance tracking logic.
Built a secure financial operations layer with validation and atomic DB transactions.
Implemented activity logging and audit trails; optimized high-frequency queries with indexes and caching.

WebSockets PostgreSQL Redis
 Flowscore SPORTS DATA & ANALYTICS

Integrated third-party sports data APIs.
Built a REST API layer for match data, statistics and team information.
Implemented a proxy architecture to normalize external API responses.
Designed scalable data models for sports events and a caching layer to reduce API calls.

REST API Node.js Caching

NutrimateAI AI NUTRITION PLATFORM

Integrated AI APIs (LLM) for generating personalized meal plans.
Implemented user profile logic: dietary preferences, calorie goals and restrictions.
Designed a relational PostgreSQL schema for users, plans and analytics.
Developed token-usage tracking and rate-limiting mechanisms.

LLM APIs PostgreSQL Rate Limiting

// education Education & Languages

M.Sc. Information Systems & Technologies Ukrainian Native
Khmelnytskyi National University · 2024 — 2025 Russian Fluent
B.Sc. Computer Engineering English Intermediate
Khmelnytskyi National University · 2020 — 2024

Oleh Voloshyn — Backend Engineer github.com/Sledgeee