Martin Trenker

Consultant & Technical Lead

Engaged as React expert and consultant to modernise the POS software running in ~1,800 Douglas stores across 26 European countries. Led the full rewrite of a complex, hard-to-maintain CRM integration from legacy code to a clean React architecture — shipped in under a year. Also responsible for the customer care app (Angular, maintenance) and greenfield tooling.

• rewrote the entire CRM/POS integration from scratch in under a year — every aspect improved: architecture, testing, documentation
• software runs on every cash register in ~1,800 stores across 26 European countries
• shifted from fear-driven 9pm deployments to deploy-any-time by introducing resilience and self-healing patterns
• onboarded 1 senior and 2 junior developers; all productive contributors within weeks
• introduced "Full Stack Fridays" — team-driven learning sessions covering Figma prototyping, GraphQL/C#/.NET, and more
• built an in-house shortlink and QR service in Next.js + .NET in weeks, replacing a third-party SaaS that no longer met business needs
• led responsible AI adoption across the team — tooling, practices, and guardrails

Solutions Architect

Managed the handover of a Next.js platform from an external agency to a newly formed in-house team — audited the codebase, merged two products, and got the team up to speed.

• audited and raised code quality across the full stack: Next.js, TypeScript, GraphQL, Apollo, Cypress, Storybook, Tailwind
• consolidated two separate web products into a single codebase without disrupting active development
• onboarded four new hires in parallel while keeping delivery on track
• introduced lightweight agile practices that the team still uses

Technical Lead

Led a three-person team building a data-heavy internal web app in TypeScript and React, with a strong focus on mentoring two junior developers.

• daily pair-programming with two juniors — both grew into independent contributors within weeks
• tracked down and resolved chronic render-cycle bottlenecks, cutting page interaction time noticeably

Technical Architect

Rewrote a complex AngularJS optometry workflow app in TypeScript/React, replacing ad-hoc state logic with XState-driven form architecture for in-store staff.

• daily pair-programming as the main knowledge transfer strategy — worked exceptionally well
• state-machine driven multi-step form architecture built for extensibility
• custom on-screen keyboards tailored to in-store workflows

Engineering Consultant

Built a real-time communication micro-frontend handling VoIP calls between customers and mortgage advisors, using React, Redux Toolkit and WebRTC.

• doubled as agile coach, introducing practices that noticeably reduced sprint friction
• first production WebRTC integration — shipped without third-party SDK

Frontend Engineer

Built and maintained React components powering high-traffic show websites for ProSieben and Sat.1 formats, with GraphQL APIs and analytics tracking throughout.

Frontend Engineer

Built a React + GraphQL web magazine for Germany's largest online car dealer, connected to a headless CMS.

Frontend Engineer

Built components for an online travel magazine using React, TypeScript and GraphQL, backed by Contentful as a headless CMS.

• adopted Contentful as headless CMS before the pattern became industry standard

Frontend Engineer

Developed React components for Lufthansa's digital touchpoints, integrated into Adobe Experience Manager.

• accessibility as a hard requirement, not an afterthought
• component library built for editorial reuse across markets

Real-time Web Systems Engineer

Built real-time monitoring dashboards served directly on industrial machines, using native web components years before they went mainstream.

• early adopter of native web components via Polymer in a production manufacturing context

Technical Lead

Delivered a QR-code-based badge management system for staff and visitors, including on-demand print integration.

Technical Lead

Rearchitected a legacy migration tool from scratch — moved to Symfony + React with CQRS-backed data structures, significantly improving maintainability and auditability.

• introduced CQRS — a rare pattern in PHP shops at the time

Fullstack Developer

Built a multi-region dealer evaluation platform for BMW, supporting both customer-facing and internal staff surveys across global markets.

• hierarchical evaluation model: store → local → regional → country — each level saw exactly the data their role required
• first AngularJS application — adopted before the framework was mainstream in enterprise contexts
• multi-region, multi-language rollout across BMW's global dealer network

Fullstack Developer

Maintained a worldwide hardware migration tracking system used across McKinsey offices globally, built on Zend Framework and Oracle DB.

Fullstack Developer

Owned a full-stack auction platform used for a company-wide annual charity event — from database schema to frontend, soup to nuts.