TanStack Query Experts in Germany

• Own full-stack development of an AI-native enterprise platform built on TypeScript, React, Vite, tRPC, Hono, and PostgreSQL, delivering AI-powered consulting workflows to B2B clients.
• Designed and shipped a multi-agent AI system using ReAct framework and Claude skills-style workflow patterns, including an intelligent PM assistant with rich system prompts, slash commands, tool integrations, and streaming chat UI.
• Architected an LLM evaluation framework: rubric-based LLM-as-judge, golden datasets, regression testing, and automated quality gating — ensuring consistent AI output quality at scale.
• Integrated LangFuse for end-to-end LLM tracing, conversation replays, and evaluation pipelines, enabling data-driven prompt optimisation that reduced token costs and response variance.
• Built with Drizzle ORM, pgvector, and knowledge graphs for structured data access, semantic search, and relationship-aware AI reasoning across the platform.
• Led TanStack React Query migration across the application — replacing manual state management with centralised caching and automatic refetching, reducing data-fetching boilerplate significantly.
• Practiced AI-native development throughout: Claude Code, Codex, Perplexity SDK, and LLM-assisted testing across the full development lifecycle. Deployed on Vercel + Azure ACA with Biome for linting/formatting.

• Founded an AI-powered scheduling and business-management SaaS for SMBs, owning technology strategy, architecture, product development, UX, billing and go-to-market execution.
• Architected and shipped a multi-tenant platform with REST APIs, RBAC, CRM, billing and notifications, powering the manager dashboard, admin console, booking experience and iOS/Android applications.
• Led and mentored 7 software engineers, 1 DevOps engineer, 1 QA engineer and 1 UX/UI designer, while remaining hands-on across backend, frontend and product delivery.
• Built AI voice and chat agents using Python/FastAPI, OpenAI and Anthropic APIs, RAG, pgvector and tool calling; integrated Twilio, Google Calendar/Meet, Stripe and Firebase.
• Owned production infrastructure and automated delivery across separate environments using Docker, Nginx, GitHub Actions and Grafana; represented the company at accelerators and international startup events.

Selected stack: Python, FastAPI, Node.js, Vue 3, React/Next.js, React Native, PostgreSQL, Redis, Docker

Project: Tax Exemption Order Application

The client has an existing application for creating and maintaining tax exemption orders for end customers; design and implementation of a comparable application for internal employees.

• Design and implementation of microservices and the UI for the business area "tax exemption orders" using Domain Driven Design as well as Spring Boot and Angular.
• Implementation of reactive, non-reactive, and asynchronous APIs (Spring REST, WebFlux, GraphQL).
• Development of the Angular application, including state management using Signals, RxJS Observables, and subscriptions.
• Securing the API and the application using OAuth2, JWT, and OpenID Connect.
• Configuration and setup of CI/CD pipelines with Jenkins.
• Collaboration with cross-functional teams and conducting code reviews.

Environment: Java, Spring Boot, Angular 18 & 19 (standalone, signals), RxJs, Bootstrap CSS, Vitesting, OpenShift, Istio, microservices, Kafka, Dynatrace, Jenkins, GitLab, Graylog, Sonar, Oauth2, OracleDB

• Built more than 15 frontend applications and more than 10 backend services across internal tools, back-office workflows, and external portals for installers and end customers
• Automate build and release workflows with TypeScript and Azure DevOps
• Mentor junior engineers through code reviews and technical guidance
• Integrate AI-assisted and agentic development practices into engineering workflows
• Coordinate user experience decisions with UX designers

Tech Stack: Claude Code, Codex, AWS (S3, Lambda, AppSync, Resolver), Next.js App Router, ReactJS, NuxtJS, Vue.js, Storybook, JavaScript, TypeScript, GraphQL, Azure DevOps

• Responsible for the entire software architecture of the parental allowance portal
• iOS and Android app with React Native and Expo, incl. push and OTA updates
• Store releases via App Store Connect and Google Play Console
• TypeScript monorepo for app, website and backend, web with Next.js and Tailwind
• Own promo, voucher and discount engine with contact and segment logic
• Payments via RevenueCat and in-app purchases, authentication with BetterAuth
• REST APIs based on OpenAPI, PostgreSQL with Prisma and Drizzle
• Self-hosting on Hetzner with Docker, Coolify, Terraform and GitHub Actions
• Tests with Vitest, Playwright and visual regression via Chromatic
• Observability via Grafana Cloud and error tracking with Sentry
• Performance marketing via Meta Ads, measured with custom event tracking
• Grew the product to 20,000 app users with a purchase rate of almost 12 %
• Managing Director since 04.2025, responsible for product and technology

• Technical leadership in the implementation of accessible frontend components with React and MUI

• Analysis and refactoring of existing UI structures with regard to semantic HTML usage, ARIA roles, and keyboard navigation

• Integration and use of accessibility testing tools such as Axe and Lighthouse

• Close coordination with UI/UX design, backend development, and QA to ensure a consistent a11y-compliant user experience

• Advising the client on implementing legal requirements according to BITV 2.0 / EU Directive 2016/2102

• Improved the Lighthouse Accessibility Score from 55 to 98

• Long-term improvement of the codebase through the introduction of reusable, accessible components

• Positive client feedback and follow-up work for future a11y projects

• Tools and technologies: React, MUI, TypeScript, JavaScript, HTML5, CSS3, Node.js, WCAG 2.1 AA, Axe, Lighthouse, SCRUM, Agile, Jira, Bitbucket

• Sole owner of all frontend architectural decisions, technology choices, component structure, build pipeline, and standards across the AnzaKen website and product builds
• Built production React components and coached a junior developer through component patterns, state management, and modern frontend practices via pair programming and code review
• Built products and internal tooling with React and Next.js using Claude Code, RAG pipelines, and AI guardrails, emphasizing maintainability, API integration, and delivery speed
• Participated in client pitches and discovery meetings, scoped technical needs, advised on feasibility, and shaped proposals
• Stack: React, TypeScript, Next.js, Node.js, Python, FastAPI, PostgreSQL, Claude Code, RAG, Vercel, Render

• Significant enhancement of the B2B React SPA software "opti.node" for commercial operations management for renewable energy plant operators
• Introduced features not previously available on the market, resulting in a significant revenue increase
• Comprehensive automated tests within Storybook
• Introduced a UI library to improve developer experience and speed up feature development by about 40%
• Clear presentation of complex commercial and legal issues, with intuitive UX and UI
• UX consulting to shorten essential interaction flows by 75%

• Development of a CMS-based online platform as a central hub for multimedia brand communication, focusing on accessibility, web performance, and data protection.
• Technologies: PHP, Craft CMS, Twig, HTML, CSS, JavaScript, Alpine.js, htmx.

• Implemented and maintained logistics-domain applications using Angular, C#, ASP.NET, HTML5, CSS3, JavaScript, AJAX and Bootstrap
• Analyzed, designed, coded and deployed backend services and integrations using .NET, XML Web Services and RESTful APIs
• Developed automated SSIS packages and scheduled ETL jobs to support data workflows
• Built and maintained Python scripts for automation and prototyping; applied Cursor AI to build/refactor full-stack AI/ML model integrations
• Implemented unit and integration testing (NUnit) and conducted performance tuning for backend services
• Managed source control and CI/CD using GitHub, Azure CI/CD pipelines and TeamCity

• Built modern web applications using React and NestJS.
• Developed frontend with React, TailwindCSS, shadcn/ui for elegant and responsive interfaces.
• Implemented backend APIs and authentication using NestJS and Node.js.
• Utilized AWS and Supabase for cloud deployments.
• Integrated Salesforce for CRM and data management.

I worked on automating cold outreach.

• Developed a queue architecture to support the parallel execution of large volumes of background tasks.
• Integrated multiple email delivery providers.
• Implemented an LLM-based data enrichment process.

Technologies: TypeScript, React, Node.js, Next.js, Drizzle ORM, PostgreSQL, Next-Auth, JWT, Docker, Kubernetes, AWS, CloudFlare, Traefik, Groq, Jest, Figma

• Code & project cleanup to accommodate multiple developers
• Implemented project linting (ESLint, Prettier, Husky Hooks)
• Refactored application routing and authentication logic (ReactJS, Next.JS, Recoil)
• Implementing vital UI ideas as standalone features into an administration dashboard (ReactJS, Tailwind CSS, Next.JS, TypeScript)

• Teaching JavaScript, HTML, CSS, React, NodeJS, MongoDB, MariaDB, and Express
• Designing and preparing lessons
• Classroom teaching and one-on-one coaching