Олександр

OLEKSANDR SOKOLOVSKYI
Full Stack Developer — Node.js / React Native / React
Vinnytsia, Ukraine · [open contact info](look above in the "contact info" section) · [open contact info](look above in the "contact info" section)

SUMMARY
Full Stack JavaScript/TypeScript developer with 5+ years of experience delivering e-commerce, delivery and logistics products end-to-end —
from requirements analysis and API design to production support. Integrated payment providers (Stripe, Adyen, PayPal, Klarna, Google Pay)
in a live e-commerce platform; designed REST, gRPC and GraphQL APIs on Node.js (NestJS, Express.js); shipped React Native applications
used in daily operations. Integrated LLMs into products (MCP servers, AI assistants) and set up AI-assisted development workflows for
teams. Strong in PostgreSQL, Docker, CI/CD, automated testing (unit, BDD e2e with Playwright) and code review.

TECHNICAL SKILLS

Backend Node.js, TypeScript, JavaScript, NestJS, Express.js, AdonisJS, REST API, oRPC, gRPC, GraphQL, WebSockets,
Microservices, BullMQ, TypeORM, Prisma, Drizzle ORM, nestjs-cls, JWT, RxJS
Frontend React, Next.js (SSR), Vite, Feature-Sliced Design, React Hook Form, Zod, Redux Toolkit, shadcn/ui, Storybook,
Tailwind CSS
Mobile / Notifications React Native, Push Notifications, Web Push (VAPID), Telegram Bot API, Google Maps SDK
Databases PostgreSQL, MySQL, MongoDB, Redis, Elasticsearch
Payments / FinTech Stripe, Adyen, PayPal, Klarna, Google Pay, 3-D Secure, payment webhooks, refunds, State Tax Service of Ukraine
(DPS) API
Infrastructure / DevOps Docker, nginx, RabbitMQ, Grafana, GitHub Actions CI/CD, GitLab CI/CD, GHCR, n8n (workflow automation)
Testing Playwright, BDD (Gherkin / Cucumber), PactumJS (API integration tests), WebdriverIO, Jest, MSW, unit & e2e
testing
AI / Automation LLM API integration, MCP servers & tools, Claude Code (agents, CLAUDE.md, skills, MCP), AGENTS.md, prompt
design
Process Requirements gathering & analysis, technical specifications, backlog grooming, contract-first API design, code
review & quality gates, system design, Jira, Agile/Scrum, cross-functional collaboration with product and
operations teams

EXPERIENCE
Frontend Engineer (full-stack scope) — DIFFREIGHT, logistics ERP platform · Kyiv (on-site) Feb 2026 — Present
ERP platform for freight forwarding and logistics operations. React/Vite frontend; NestJS backend with PostgreSQL.
Design system architecture and business workflows together with the product and operations teams: gather and analyze requirements,
produce technical specifications and estimates, and translate business goals into implementation plans.
Develop the financial module of the ERP: invoicing, payments and settlements with clients and carriers, multi-currency support and
financial reporting.
Lead the incremental migration of a legacy Node.js backend to NestJS (Strangler Fig pattern) with nginx routing and a shared PostgreSQL
schema — zero downtime, feature delivery unblocked.
Introduce a contract-first API workflow: a shared type-safe oRPC contract package between frontend and backend, with mocks and
TypeScript compilation as contract verification.
Build frontend features with React, Vite, Feature-Sliced Design, React Hook Form + Zod and Storybook; design filter and data-grid UI
backed by SQL predicate logic (scalar, array, JSONB).
Set up CI/CD on GitHub Actions with Docker-based per-PR preview environments, production health monitoring (Grafana alerts → Slack)
and a Playwright e2e suite (BDD, Gherkin) as a post-deploy check.
Establish the team's engineering process: backlog grooming workflow, Jira conventions and code quality gates (PR review,
ESLint/TypeScript strict checks, automated CI checks).
Set up AI-assisted development with Claude Code: agents, MCP tools (Jira, Figma, Playwright, browser), team conventions and skills;
design a multi-agent pipeline for task execution (research → analysis → spec → implementation → review → e2e).
Build Telegram bots on Node.js for operational notifications and team workflows; automate GitHub → Jira → Slack pipelines with n8n; work
with RabbitMQ, Elasticsearch and Redis in the platform stack.
Full Stack JavaScript Developer — Seezona AB · Remote Sep 2023 — Jan 2026
International fashion e-commerce marketplace for independent designers.
Designed and implemented backend services on NestJS with PostgreSQL and frontend features on Next.js (SSR) / React.
Integrated and maintained payment providers — Stripe, Adyen, PayPal, Klarna — including checkout, refunds and webhook processing.
Implemented real-time order and status updates via WebSockets; optimized system performance and stability.
Gathered and analyzed business requirements with product owners, turned them into technical specifications; performed code reviews for
the team.
Built e2e coverage with WebdriverIO + Cucumber (BDD) and unit tests with Jest.
Integrated AI into the platform: built an in-house MCP server exposing CRM data and actions as tools, and an AI chat assistant inside the
internal CRM for managers (order lookup, customer and designer support workflows).
Implemented AI-powered processing of newly listed products: automatic description generation, attribute extraction and categorization.
Adopted Claude Code as the team's AI coding assistant: configured agents, MCP tools and CLAUDE.md/skill conventions; used daily for
feature development, refactoring and test generation.
Full Stack JavaScript Developer (part-time) — Real estate company · Remote Jun 2025 — Sep 2025
Refactored the codebase to Feature-Sliced Design, extracted shared types, configured ESLint rules; improved the CI/CD pipeline.
Full Stack JavaScript Developer — ONTHEWAY · Remote May 2022 — Sep 2023
Delivery logistics platform: React Native mobile app + web admin panel. Still in daily production use.
Architected NestJS microservices communicating over gRPC; PostgreSQL and GraphQL data layer; Docker containerization.
Built the React Native app for creating and tracking delivery orders with Google Maps routing and push notifications for real-time status
updates.
Built the web admin panel (React, Redux Toolkit, TypeScript) for order, user and analytics management.

Full Stack JavaScript Developer (part-time) — Tour club "Bidnyazhka" · Vinnytsia Apr 2021 — May 2025
Developed a tour booking web app (search, filters, online payment) and a React Native app for organizers (group management, routes,
notifications).
Next.js / REST API backend, MySQL, Docker; React, Redux, Formik on the frontend.
Mobile Developer — HoF, smart-home control system · Vinnytsia Sep 2020 — Feb 2021
Built a React Native app with a Node.js / Express.js REST backend on MongoDB: JWT authentication, real-time sensor data, role-based
access (guest/family), configurable notification thresholds, web admin panel. In production since 2021.

PROJECTS
Finsomar — CRM for outsourced accountants (own product) Ongoing
CRM for accounting and management-accounting outsourcing: accountants manage multiple client companies (sole proprietors and LLCs),
their financial data, tax deadlines and reporting in one workspace.
Designed and built the full stack solo: NestJS backend with Drizzle ORM on PostgreSQL, oRPC type-safe contract shared with a React +
shadcn/ui frontend, Zod validation on both sides.
Implemented multi-tenant JWT authentication (accountant → client companies) with refresh tokens and role-based access; request-scoped
tenant context via nestjs-cls.
Integrated the State Tax Service of Ukraine (DPS) API to sync client registry data, tax obligations and reporting deadlines
automatically.
Built background processing with BullMQ (Redis): scheduled tax-deadline reminders, report generation and DPS data sync jobs with
retries and dead-letter handling.
Implemented multi-channel notifications for accountants and their clients: Web Push (VAPID, service worker) and a Telegram bot for
deadline reminders and status updates.
Covered the API with automated integration tests using PactumJS; unit tests with Jest.

EDUCATION
M.Sc., Automation, Computer-Integrated Technologies and Robotics — Vinnytsia National Technical University, 2024 — 2025

LANGUAGES
Ukrainian — native · English — Upper-Intermediate (B2), professional working proficiency