# Vasyl Semiliak

Independent Software Engineer — Frontend, Design Systems & Developer Experience

Warsaw, Poland | Remote (EU-based, EST overlap) | +48 453 076 204 | hello@vasylsemiliak.com

[linkedin.com/in/vasylsemiliak](https://linkedin.com/in/vasylsemiliak) | [github.com/vasylsemiliak](https://github.com/vasylsemiliak) | [vasylsemiliak.com](https://vasylsemiliak.com)

Independent frontend/platform engineer with 10+ years building complex product UI, design systems, and the internal tooling that lets teams ship faster without sacrificing quality. Now partnering directly with product teams on contract to strengthen frontend foundations and derisk delivery across React, TypeScript, and Next.js.

## Work Experience

### Independent Software Engineer — Jun 2026 - Present

Frontend Consultant — Contract & Client Work | Remote | EU-based

- Took over a geospatial platform's unreliable large-file uploads — roughly 70% of 1GB+ transfers failed with no way to resume — and rebuilt them as a browser-native engine (Web Workers, SQLite WASM, OPFS, resumable S3 multipart): completion reached 99.7% and peak memory dropped from gigabytes to ~50MB.
- Lead AI-driven engineering for multiple clients (Claude Code, MCP, custom agent skills): building agentic workflows that implement, test, and debug complex features end-to-end, letting small product teams ship on larger-team timelines.

### Corellium — Oct 2021 - May 2026

Frontend Systems Engineer | United States | Remote

- Shipped the internal design-system foundation (React, Storybook, TypeScript, Tailwind) and Vite migration: -40% component cycle time, -90% build time, ~5 h/week saved — faster, more consistent frontend delivery across the team.
- Cut production errors 50% and deploy failures 30% via typed API contracts, lint rules, and Playwright CI gates: stronger release confidence for a US security SaaS serving enterprise and government customers.
- Modernized core frontend foundations — JavaScript-to-TypeScript, latest Node LTS, and ESLint/Prettier/Stylelint: -20% dev time, +40% maintainability.
- Re-platformed the state layer (TanStack Query + Context) and automated dependencies with Renovate: -30% codebase, removed 60% of Redux.

### Rolique — Oct 2018 - Oct 2021

Frontend Product Engineer (Fintech & Healthcare SaaS) | Lviv, Ukraine

- Led frontend architecture and cross-functional coordination on a complex React/GraphQL fintech dashboard: shipped 100% of roadmap epics on schedule for three consecutive quarters.
- Shipped a TypeScript + Axios SDK from Swagger specs (REST-to-frontend code-gen): cut development time 30% and sharply reduced integration bugs across web and React Native healthcare apps.
- Established scalable delivery patterns and an OpenAPI-to-GraphQL gateway with automated tests: enabled continuous weekly releases and faster team onboarding.

### Ralabs — Oct 2017 - Oct 2018

Full-Stack Product Engineer (Fintech & Web Platforms) | Lviv, Ukraine

- Built crypto-exchange integrations and data-normalization microservices automating transaction capture: cut new-customer onboarding friction ~80% for a tax platform.
- Shipped early product iterations on schedule, including a full Meteor.js MVP (React + Node): enabled first pilots and faster product validation.

### AXSYS Inc. — Jul 2016 - Oct 2017

Founding Engineer | Lviv, Ukraine

- As founding engineer, built product and infrastructure from zero to first market-ready release: won early customers and secured accelerator acceptance.
- Built client-facing integrations, including an embeddable Stripe booking flow with Twilio/SendGrid notifications (99.9% messaging reliability): expanded distribution and opened a new revenue stream.

## Education

- Lviv Polytechnic National University — 2014 - 2019

## Skills

**Frontend & Platform:** React, React Server Components, React Compiler, TypeScript, Next.js, Node.js, Design Systems, Storybook, Tailwind CSS, shadcn/ui, TanStack Query & Router, GraphQL, REST, React Native, Vite, pnpm, monorepos, GitLab CI/CD, Playwright, Core Web Vitals (LCP/INP/CLS), Accessibility (WCAG 2.2), AWS, Docker, Stripe.

**AI / Agentic Engineering:** Claude Code, Cursor, MCP (Model Context Protocol), Agent Skills (SKILL.md) — directing AI agents to implement, test, and debug complex features.

## Languages

Ukrainian (Native) | English (Full Professional)

---

PDF version: [vasylsemiliak.com/vasyl-semiliak-cv.pdf](https://vasylsemiliak.com/vasyl-semiliak-cv.pdf)