Олег

Oleh Chaplia
Full-Stack Engineer
[open contact info](look above in the "contact info" section) | Lviv, Ukraine — open to remote | [open contact info](look above in the "contact info" section) |
[open contact info](look above in the "contact info" section) | github.com/oleg191006

SUMMARY
Full-Stack Engineer with 1.5 years of hands-on experience on an enterprise-scale microservices
platform (~2,000 repositories) for a US real estate company. Build and ship features across
React/TypeScript frontends and Node.js/Express/NestJS backends, including event-driven
integrations with third-party APIs, authentication migration, and production data-integrity and
performance fixes.

EXPERIENCE
SoftServe Lviv, Ukraine · Mar 2025 – Present

Full-Stack Engineer · Hybrid Oct 2025 – Present
Microservices-based real estate platform for the US market.
Built an event-driven integration with the LoneWolf document-management API, including scheduled retry
logic for failed operations — from technical spike through production rollout.
Root-caused a cross-team notification failure in a third-party API and led the migration to the new API
version, coordinating cross-service testing with the affected teams.
Migrated the team's service to the company-wide authentication approach (STS SDK with Vault-managed
secrets), sequencing the rollout around dependent teams to avoid downtime.
Diagnosed and fixed a production-only data-integrity bug in user financial calculations, tracing it to legacy
fields left by historical data migrations.
Optimized a high-traffic data table by eliminating redundant network requests, and resolved a UI race
condition using request cancellation.
Contributed to day-to-day feature development and code reviews, coordinating with QA, PM and business
stakeholders across sprint cycles.
Tech · React · TypeScript · Node.js · Express.js · NestJS · Microservices · Event-Driven
Architecture · Pub/Sub · Redis · PostgreSQL · MySQL · GCP · Docker

Full-Stack Engineer, Internship · Remote Mar 2025 – Sep 2025
Space2Study — tutoring platform connecting students with tutors. Built the React/TypeScript frontend with
Redux state and the Express REST API behind it, designed the MongoDB schemas, and implemented
authentication and the session-scheduling logic. Added unit and integration tests with Jest and Vitest.
Liatoshynsky Foundation — production site for a charitable foundation. Built the Next.js/TypeScript SSR
application with dynamic routing, reusable MUI components and MongoDB-backed API routes, tuning
server-side rendering for performance and SEO. Core flows covered with Jest.

WinWin.travel Remote · Dec 2025 – Mar 2026

Frontend Developer · Volunteer, part-time · React 19 / React Router 7 SSR
Migrated the shared configuration module out of a legacy library tree into the Feature-Sliced Design layer
structure, rewriting imports across every layer and removing the obsolete TypeScript path mappings.
Enabled an incremental Chakra UI → Radix UI design-system migration with lint-level deprecation rules
that flag every component still awaiting migration.
Shipped features across search, maps and notifications — geocoding autocomplete with fallbacks,
responsive Leaflet/MapLibre map controls, and a toast hook with hover pause/resume.
Tech · React 19 · TypeScript · React Router 7 · Feature-Sliced Design · TanStack Query &
Table · Zustand · Radix UI · Tailwind CSS · Leaflet/MapLibre · i18next · Vitest · MSW ·
Storybook

PROJECTS
Rooms · meeting-room booking app · NestJS + React monorepo 2026
TypeScript monorepo — a NestJS/Prisma/PostgreSQL API, a React client, and shared packages holding the
domain rules and Zod contracts both sides import, so client and server validate identically. JWT/argon2
auth, recurring weekly bookings in one transaction, end-of-booking alerts over server-sent events.
Prevented double booking under concurrency with a PostgreSQL exclusion constraint over a tstzrange
rather than locking — a test fires two identical requests at once and asserts one 201, one 409 and exactly
one row.
Stored times as instants and resolved office hours in the office timezone with Luxon, so schedules and
weekly recurrence survive daylight-saving changes. 14 ADRs record the design decisions.
Tech · TypeScript · NestJS · Prisma · PostgreSQL · React · TanStack Query · Zod · Luxon ·
Tailwind CSS · Vite · Jest · Supertest · Docker Compose · npm workspaces

github.com/oleg191006/room-booking

Release Watcher · Genesis Academy capstone · Node.js microservices 2026
GitHub release notifier split into a main API and a notification service over three transport paths — a
BullMQ queue, gRPC, and a REST fallback — with a saga orchestrator for the subscribe flow and a cron
scanner backed by a Redis cache.
Prometheus metrics with a Grafana RED dashboard, structured Winston logging, and four test layers — unit,
integration, Playwright end-to-end and architecture-dependency — across four GitHub Actions workflows,
with ADRs and a design doc.
Tech · Node.js · Express · PostgreSQL · Redis · BullMQ · gRPC (Protobuf/Buf) · Prometheus
· Grafana · Winston · Docker Compose · Jest · Playwright

github.com/GenesisEducationKyiv/software-engineering-school-6-0-oleg191006

SKILLS

CORE TypeScript, JavaScript, React, Node.js, NestJS, Express.js, PostgreSQL
FRONTEND Next.js, Redux, Zustand, TanStack Query, Tailwind CSS, Material UI, Radix / shadcn/ui, Zod, CSS/SCSS,
Storybook, Feature-Sliced Design
BACKEND & DATA REST APIs, GraphQL, gRPC, Microservices, Event-Driven Architecture (Pub/Sub, BullMQ), MySQL, MongoDB,
Redis, Prisma ORM
TESTING Jest, Vitest, React Testing Library, Supertest, Playwright, MSW
AI / LLM Claude API, Agent SDK, tool use, structured output
INFRASTRUCTURE Git, Docker, GCP, CI/CD (GitHub Actions, Harness), Prometheus, Grafana, monorepos (npm/pnpm
workspaces)

E D U C AT I O N & C E R T I F I C AT I O N S
Bachelor's Degree in Computer Science · Ivan Franko National University of Lviv 2023 – 2027 (expected)

Software Engineering School · system architecture, databases, observability Genesis Academy · Jul 2026

Claude Certified Developer — Foundations 896 / 1000 Verify ↗ Anthropic · Aug 2026
Claude API, Agent SDK, tool use and structured output.

Languages · English — B2 · Ukrainian — Native