# Andrii Sirko

> Senior frontend engineer and full-stack contractor with over ten years building production React applications for European technology companies including ABOUT YOU, eBay (Adevinta), Daimler/smart, Volkswagen/Audi and Careem. Frontend lead at 1M+ monthly-active-user scale and engineer on ABOUT YOU’s 40M+ MAU e-commerce platform, specialising in TypeScript, component architecture, monorepos and performance.

Andrii Sirko is a senior frontend engineer and full-stack contractor based in Berlin, Germany, working remotely across European time zones and available for contract work.

- Website: https://andrii-sirko.github.io/
- Email: andrii.sirko@gmail.com
- LinkedIn: https://www.linkedin.com/in/andrii-sirko
- GitHub: https://github.com/andrii-sirko
- Location: Berlin, Germany
- Languages: Ukrainian (native), English (fluent, B2), German (fluent, C1)

## Core expertise

- **Core**: React, TypeScript, Next.js, Node.js
- **Mobile**: Ionic, React Native
- **Backend**: NestJS, TRPC, GraphQL, gRPC, Prisma, PostgreSQL, MongoDB
- **Testing**: Jest, Cypress, Playwright, Storybook, k6
- **Infra**: AWS, Docker, CI/CD, Kubernetes
- **AI / LLM**: RAG, OpenAI API, LLM integration

## Notable outcomes

- Reduced client onboarding from 4 months to 30 minutes by architecting a reusable
  React application framework (Mehrwerk).
- Built a UI Editor serving real-time content to 1M+ monthly active users across web
  and native platforms (Mehrwerk).
- Shipped a white-label Dealer Search used on Audi.de across 90+ markets, integrated
  as a micro-frontend (Accenture · VW / Audi).
- Owned a full k6 load-testing suite — smoke, stress, soak and spike — for SSR and
  GraphQL services (Mehrwerk).
- Led a team of 5 engineers as Frontend Lead over a four-year engagement (Mehrwerk).

## Engagement history

### ABOUT YOU — Senior Frontend Engineer
June 2026 – Present · Contract · Remote · aboutyou.de

Customer-facing features in a large-scale React/TypeScript e-commerce monorepo powering the mobile and desktop web shops, with a gRPC data layer and container/presentational package architecture.

- Delivered the loyalty Status Program end-to-end — gRPC client integration, deep-linked routing, mobile and desktop views — from API stub to production rollout inside the Coins wallet.
- Extended the A/B testing infrastructure with dynamic activation of server-side experiments and shipped experiment winners; hardened the GA4-scale analytics layer by eliminating duplicate events and enforcing event-schema correctness.

Stack: React, TypeScript, Monorepo (Yarn workspaces), Linaria, React Query, Zustand, gRPC, Storybook, Jest, RTL, Cypress, GitLab CI

### SelectCode GmbH — Fullstack Developer
December 2025 – March 2026 · Contract · Remote · meingpt.com

An enterprise-grade, privacy-focused AI platform with RAG capabilities and multi-LLM support.

- Developed collaborative features — shared AI assistants and chat workflows — in React and Zustand.
- Implemented secure TRPC/Prisma endpoints covering organization hierarchies, RBAC via Lucia Auth, and Stripe subscriptions.

Stack: TypeScript, React, NestJS, TRPC, Prisma, PostgreSQL, Playwright, RAG, OpenAI API, Kubernetes

### Mehrwerk GmbH — Frontend Lead
September 2021 – December 2025 · Contract · Remote · mehrwerk.de

Four years leading frontend for a loyalty and benefits platform, run alongside parallel contracts.

- Led a team of 5 and architected a scalable React application framework that cut client onboarding from 4 months to 30 minutes.
- Built a UI Editor for real-time content updates across web and native, serving 1M+ monthly active users.
- Designed and owned the full load-testing suite — smoke, stress, soak and spike — for SSR and GraphQL services using k6 and Grafana Cloud.

Stack: TypeScript, React, Ionic, React Native, Next.js, Node.js, Kotlin, GraphQL, MongoDB, Jest, Cypress, AWS, k6

### eBay GmbH (Adevinta) — Senior React Developer
February 2022 – December 2022 · Contract · Remote · kijijiautos.ca

Dealer retail team on Kijiji Autos, Canada’s largest online auto platform.

- Delivered React features across the dealer-facing product surface.

Stack: React, TypeScript, ESLint, Jest, TestCafe, AWS

### Accenture · smart / Daimler — Senior React Developer
May 2021 – January 2022 · Contract · Remote · future.smart.com

The smart IAA landing page for the brand’s future product reveal.

- Implemented immersive, animated React components for a high-traffic automotive brand launch.

Stack: React, TypeScript, Styled Components, Webpack, AEM, Jest

### lemon.markets GmbH — Senior React Developer
June 2021 – September 2021 · Contract · Remote · lemon.markets

Blog and CMS surfaces for a fintech brokerage API product.

- Built custom Prismic-powered slices for Blog and CMS pages.

Stack: React, Next.js, TypeScript, Prismic, ESLint, Jest

### Accenture · VW / Audi — Senior React Developer
November 2020 – May 2021 · Contract · Remote

White Label Dealer Search, shipped across two automotive brands.

- Implemented a White Label Dealer Search app for VW and integrated it into Audi using a micro-frontend approach, supporting Audi.de across 90+ markets.

Stack: React, TypeScript, Styled Components, Webpack, Jest

### Factor Eleven — Senior React Developer
September 2019 – May 2021 · Contract · Remote · factor-eleven.de

AdManager platform and the component ecosystem around it.

- Architected and implemented a React-based AdManager application and component ecosystem.
- Built a shared UI library reused across multiple projects for consistency.

Stack: React, GraphQL, Apollo, Jest, Enzyme, Cypress, SASS, CSS Modules, Webpack, GitLab

### ToolTime — Senior React Developer
February 2020 – March 2020 · Contract · Berlin · tooltime.de

Field service management for tradespeople.

- Designed and implemented a React-based field service management application.

Stack: TypeScript, React, GraphQL, Apollo, Jest, Cypress, CircleCI, AWS

### Careem — Senior Software Developer
June 2018 – August 2019 · Full-time · Berlin · careem.com

Corporate customers department at the Middle East’s largest ride-hailing platform.

- Built React components and led architectural decisions for the corporate customers department.
- Maintained a shared Web UI library used across the Careem ecosystem.
- Contributed to LMD (last-mile delivery) and CareemNow (food delivery). Scrum master for a team of 6.

Stack: React, React Native, Redux, Saga, TypeScript, Jest, Cypress, Webpack, Kotlin, Scala, MySQL, AWS, Docker, Jenkins

### Circula GmbH — Frontend Developer
November 2017 – May 2018 · Full-time · Berlin · circula.com

Expense management for accountants and supervisors.

- Built expense management tools for accountants and supervisors.

Stack: React, Redux, Ruby on Rails, RSpec, Docker

### Mes.mo GmbH / Gastroguide — Full Stack Developer
January 2015 – October 2017 · Full-time · Stuttgart · gastroguide.de

Seven products for restaurants, built end to end.

- Architected a reservation system, website constructor, advertising system, file manager, form builder, menu builder and a REST API for mobile apps.

Stack: React, Redux, Flux, PHP, MySQL, AWS

### UKEESS — Full Stack Developer
April 2014 – December 2014 · Full-time · Lviv, UA · cma.ua

Where it started — e-commerce plugin work.

- Developed and maintained Magento plugins for e-commerce clients.

Stack: Magento, PHP

## Education

Lviv Polytechnic National University — MSc Computer Science, 2010–2015, Lviv, Ukraine.
Thesis: a context-aware web service for booking personal services.

## Full CV

- [Plain-text CV](https://andrii-sirko.github.io/cv.md)