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Oleksiy S.

Full-Stack Developer

Verified expert

Oleksiy S.

Full-Stack Developer

Verified expert

senior

Ukraine

$35/hour

English – Advanced

Ukrainian – Native

Top skills

React Node.js TS NextJS FastAPI PostgreSQL Redux Docker AWS WebSockets

Meet Oleksiy ✨

A Full Stack Developer with five years of experience building high-complexity, production-grade SaaS platforms where architecture, performance, and reliability are not optional. Oleksiy works at the system structure level, designing scalable frontend and backend architectures, leading deep refactoring efforts, and making technical decisions that affect long-term maintainability and growth.

He has delivered complex products including a media intelligence platform with real-time analytics dashboards and AI-powered content aggregation, a digital pathology system for medical professionals with deep zoom visualization and collaborative annotation tools, an enterprise AI NLP platform deployed across AWS, GCP, and Azure, and a multi-chain cryptocurrency wallet supporting staking, DeFi protocols, and real-time portfolio tracking.

Oleksiy combines strong React and Next.js frontend architecture with Python and Node.js backend capability, working across WebSockets, GraphQL, REST APIs, and cloud infrastructure. He regularly leads frontend teams, establishes coding standards, drives performance optimization, and contributes to backend development using FastAPI and SQLAlchemy.

If your product needs an engineer who can own system architecture, lead technical decisions, and deliver production-ready full-stack platforms that scale without breaking, Oleksiy is the kind of developer who builds things right the first time 🚀

Download the CV

Hard skills

JavaScript

TypeScript

Python

Node.js

React

Next.js

Redux

Redux Toolkit

Zustand

RTK Query

React Query

React Hook Form

Formik

Tailwind CSS

Shadcn

Material UI

Ant Design

Bootstrap

Framer Motion

tRPC

GraphQL

WebSockets

Socket.IO

REST APIs

Express

Fastify

NestJS

Medusa.js

FastAPI

SQLAlchemy

Alembic

TypeORM

Prisma ORM

Web3

SQL

PostgreSQL

MySQL

SQLite

MS SQL Server

Redis

MongoDB

Firebase

Docker

Docker Compose

Terraform

Kubernetes

Nginx

Apache

AWS

GCP

Microservices Architecture

Software Architecture

Design Patterns

Technical Documentation

TDD

Tools

Git

GitHub

GitLab

Bitbucket

GitHub Actions

GitHub CI/CD

Postman

Jest

Vitest

Pytest

Cypress

Playwright

Storybook

CodeceptJS

MSW

React Testing Library

Sentry

ESLint

Prettier

Husky

Vite

Webpack

Turbopack

SWC

VS Code

WebStorm

Cursor

PyCharm

Sanity CMS

Cheerio

Selenium

BeautifulSoup

Scrapy

OpenAI

NextAuth

AG Grid Enterprise

AG Charts Enterprise

Recharts

OpenSeadragon

Annotorious

Soft skills

Architectural thinking

Technical leadership

Problem solving

Ownership

Communication

Team collaboration

Performance mindset

Continuous learning

Media Intelligence and Content Analysis Platform

Full Stack Developer

Duration:

1.5 years

Domains:

Content Aggregation Analytics & Intelligence

Project Description:

Built the entire frontend from scratch using Next.js and React with scalable, modular architecture. Developed real-time analytics dashboards with interactive visualizations, entity extraction, sentiment analysis, and content trend monitoring. Contributed to backend development using FastAPI and drove significant performance optimizations across the application.

Tools & Technologies:

Python, TypeScript, React, Next.js, Redux Toolkit, Socket.IO, Tailwind CSS, Radix UI, Shadcn, Framer Motion, AG Grid Enterprise, AG Charts Enterprise, Recharts, React Hook Form, Yup, Cypress, Jest, ESLint, Prettier, Husky, Sentry, NextAuth, RTK Query, Firebase, FastAPI, PostgreSQL, OpenAI, Google Cloud Platform

Digital Pathology Slide Viewer and Annotation Platform

Full Stack Developer

Duration:

1.5 years

Domains:

Healthcare Technology Digital Pathology Medical Imaging

Project Description:

Led frontend development as Technical Lead for a digital pathology platform enabling pathologists to review, annotate, and collaborate on high-resolution whole slide images. Built the complete slide visualization and annotation system on top of OpenSeadragon with custom drawing tools, real-time collaborative annotations via Socket.IO, and performance optimization for handling hundreds of annotations simultaneously.

Tools & Technologies:

Python, TypeScript, React 19, Vite, Redux Toolkit, RTK Query, Material UI, Socket.IO, OpenSeadragon, Annotorious, React Hook Form, Zod, FastAPI, SQLAlchemy, PostgreSQL, Redis, Docker, Google Cloud Platform

AI SaaS Platform for Natural Language Understanding

Full Stack Developer

Duration:

1 year

Domains:

AI & Machine Learning NLP Data Analytics

Project Description:

Developed a standalone Survey Service microservice using Next.js, built interactive NLP dashboards and reporting tools, and led the technical migration from React 16 to React 18. Established comprehensive testing infrastructure with Jest and Storybook, and contributed to backend development using FastAPI and Python.

Tools & Technologies:

Python, TypeScript, React 16, React 18, Next.js, Redux Toolkit, RTK Query, Tailwind CSS, Material UI, Ant Design, FastAPI, PostgreSQL, SQLAlchemy, Jest, Storybook

Multi-Chain Cryptocurrency Wallet Application

Full Stack Developer

Duration:

1 year

Domains:

Cryptocurrency Blockchain DeFi

Project Description:

Developed a cross-platform mobile cryptocurrency wallet supporting multi-chain staking, DeFi access, and real-time portfolio tracking across Ethereum, Polkadot, Cosmos, and other networks. Built the mobile application using Ionic and React, architected backend microservices with Node.js and Fastify, and implemented AWS infrastructure using Terraform with Redis caching and CI/CD pipelines.