# Andrii Sirko

**Senior Frontend Engineer · Full-Stack Contractor**

andrii.sirko@gmail.com · +49 176 4340 4914 · Berlin, Germany
[andrii-sirko.github.io](https://andrii-sirko.github.io/) · [LinkedIn](https://www.linkedin.com/in/andrii-sirko) · [GitHub](https://github.com/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.

## Core skills

**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

## Experience

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

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** · Contract · Remote · meingpt.com
*December 2025 – March 2026*

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** · Contract · Remote · mehrwerk.de
*September 2021 – December 2025*

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** · Contract · Remote · kijijiautos.ca
*February 2022 – December 2022*

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** · Contract · Remote · future.smart.com
*May 2021 – January 2022*

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** · Contract · Remote · lemon.markets
*June 2021 – September 2021*

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** · Contract · Remote
*November 2020 – May 2021*

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** · Contract · Remote · factor-eleven.de
*September 2019 – May 2021*

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** · Contract · Berlin · tooltime.de
*February 2020 – March 2020*

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** · Full-time · Berlin · careem.com
*June 2018 – August 2019*

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** · Full-time · Berlin · circula.com
*November 2017 – May 2018*

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** · Full-time · Stuttgart · gastroguide.de
*January 2015 – October 2017*

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** · Full-time · Lviv, UA · cma.ua
*April 2014 – December 2014*

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 · Lviv, Ukraine · 2010–2015

Thesis: context-aware web service for booking personal services. Coursework included
building a compiler in C/Assembler and implementing virtual desktops for Windows 7
using the WinAPI.

## Languages

Ukrainian (native) · English (fluent, B2) · German (fluent, C1)

## Interests

Powerlifting (Candidate Master of Sport) · Reading 25+ books a year ·
Motorcycling · Travelling (30 countries) · 3D printing