Martin Trenker

Hands-on technical leadership and software architecture for modernisation and reliable delivery. TypeScript/React/Next.js, Node.js/NestJS/Express, C#/.NET, REST/GraphQL. I support agency handovers, mentoring, code reviews and AI-assisted engineering with human review. Available from September 2026 for remote DACH engagements; on-site only in Munich and surroundings (within 50 km).

Freelance client engagement. Contract extended with broader scope across the CRM backend landscape. Extended the existing production TypeScript/Node.js API built with NestJS and Express, designed and shipped a unified C#/.NET API (REST + GraphQL), and introduced governed AI tooling for daily delivery work. Built governed agent tooling and runtime tenant configuration; integrated Entra ID/OAuth permissions.

Freelance client engagement. Engaged as React expert to modernise the POS software used in more than 1,200 Douglas stores across 14 European countries. Led the transition from a legacy Angular implementation to a maintainable React architecture and shipped the business-critical CRM integration in under a year. Improved testing, observability and recovery paths; onboarded one senior and two junior developers.

Freelance client engagement. 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. Onboarded four engineers while keeping delivery on track. Stack: Next.js, TypeScript, GraphQL, Apollo, Cypress, Storybook and Tailwind.

Freelance client engagement. 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 helped two juniors become independent contributors within weeks. Resolved render-cycle bottlenecks to improve interaction performance.

Freelance client engagement. Rewrote a complex AngularJS optometry workflow app in TypeScript/React, replacing ad-hoc state logic with XState-driven form architecture for in-store staff. Used daily pair-programming for knowledge transfer and built custom on-screen keyboards for in-store workflows. Stack: React, TypeScript, XState, Storybook and Cypress.

Done the reacts