Vitest Experts in Germany

Remote freelance role focused on Agentic AI strategy, secure application patterns, and reusable agentic workflows for a government agency.

• Development and implementation of an open-source Agentic AI strategy for a government agency, with a focus on GDPR, security, and self-hosted solutions
• Development of reusable agentic workflows and business applications that enable non-technical employees to solve business problems independently
• Implementation of nine business applications with Single Sign-On (SSO) and Azure PostgreSQL integration on Hetzner Linux servers

Techstack: Python, Streamlit, Anthropic SDK (Claude), Azure, Linux, PostgreSQL, MS SQL, Angular

• Development of an agent-based governance platform for the automated assurance of EU AI Act compliance and ODA-compliant orchestration of AI services in complex enterprise environments.

• Design and implementation of an agent-based "Mission Control" framework (Aletheia Conductor) for autonomous state monitoring and process control.

• Development of "Compliance-as-Code" (CaC) solutions based on OPA/Rego for system-wide enforcement of regulatory guardrails.

• Integration of TM Forum ODA standards (TMF630, TMF622, TMF642) to ensure interoperability and standardization.

• Building a highly available event-driven architecture using Redpanda and CloudEvents v1.0 for near-real-time event processing.

• Implementation of an audit-proof "Evidence Chain" through cryptographic linking of trace logs in preparation for automated audits.

• Tech Stack: Java 21 (Quarkus Native), TypeScript (Next.js), Redpanda (Kafka API), CloudEvents v1.0, OPA (Open Policy Agent) & Rego, TimescaleDB, ZincSearch, Redis, TM Forum ODA, Git, GitHub, Clean Code Development, Like-C4.

Built an international e-commerce platform for a multi-vendor marketplace for digital assets from scratch. Designed and operated cloud native architectures at enterprise scale.

• Designed and operated a highly scalable microservice and serverless architecture
• Built the complete cloud infrastructure with Terraform + AWS CDK in AWS
• Provisioned ECS/EKS clusters (Fargate), Application Load Balancers (reverse proxy), and Lambda functions
• Observability & tracing with CloudWatch, DataDog, Prometheus, and Grafana
• End-to-end setup with DataDog (formerly AWS CloudWatch), Prometheus, and custom Grafana dashboards
• Integration of advanced metrics (including ORM mapper) and distributed tracing with Jaeger
• Robust backup and disaster recovery strategies
• RDS Postgres backups and hourly snapshots
• Read-only, asynchronously synchronized replicas with automated master failover in emergencies
• Minute-level rollback capability through versioned Docker images on ECS and Git-based CI/CD pipelines
• Created CI/CD pipelines with GitHub Actions for automated multi-stage deployments (Dev, Testing, Prod)
• Integrated Stripe for international payment processing
• Built a marketplace payment system with multiple parties and payout routines
• Used Algolia for high-performance real-time search of digital assets on the platform
• Federation of services with GraphQL and Hasura
• Later migration to GraphQL Mesh
• Test Driven Development (TDD) - unit, integration, and E2E testing with Jest, Vitest, and Playwright
• Used Next.js / React for modern frontend applications in the nx monorepo
• Enterprise security architecture & access control
• Integration of JWT tokens with Auth0, OAuth, OIDC, IP guards, BOLA protection, and secret vaults
• Authorization concepts with RBAC, ABAC, and native Postgres Row-Level Security (RLS)
• Built internal microfrontends with Retool for fast prototyping and operational business processes

Technologies: ABAC, AWS CDK, AWS CloudWatch, AWS ECS, AWS EKS, AWS Fargate, AWS RDS, AWS S3, Algolia, Auth0, DataDog, Docker, GitHub Actions, Grafana, GraphQL, GraphQL Mesh, Hasura, JWT, Jaeger, Java, JavaScript, Jest, Kotlin, Kubernetes, Monorepo, Next.js, OIDC, Playwright, Postgres, Postgres RLS, Prometheus, RBAC, Redis, Retool, Serverless, Stripe, Terraform, TypeScript, Vitest

Procure Ai builds a procurement platform with tools to optimise purchasing and supplier management, delivering real-time analytics, cost-saving insights, and automated workflows. A common data model integrates and enriches data from multiple ERP and e-procurement systems including Ivalua, SAP, Coupa, WPS, and Jaggaer.

06/2025 – TODAY:

• Architecting and building a new AI-native procurement platform with document intelligence, an agent orchestration layer using Mastra and LLM-based workflow automation across supplier, intake and category management use-cases
• Shipped agentic engineering workflows across the development team, enabling LLM-assisted code generation and review automation, measurably reducing cycle time on repetitive development tasks
• Migrating the Design System from Material UI to shadcn/ui with Tailwind, improving consistency and reducing frontend build overhead
• Staying hands-on across frontend, backend and AI features while the engineering team grew from 10 to 20+ engineers: hiring, onboarding, 1:1s and mentoring

06/2020 – 06/2025:

• Joining as the first engineer after the two founders; shaping platform architecture and product vision from scratch in close collaboration with the CTO, growing the platform to serve 10 enterprise customers
• Leading fullstack feature development on the core procurement platform, with focus on Analytics, Search, and Autonomous Negotiations use-cases: defining MVP scope, aligning technical decisions to customer outcomes, and cutting work that wasn't delivering value
• Challenged a field-based configuration request for Autonomous Negotiations and instead built a node-based rule builder matching how category managers think in conditions and branches; later reused across other workflow and decision configuration use-cases
• Designing and implementing multi-tenant authentication and fine-grained authorisation based on organisational units
• Architecting and building a multi-tenant Admin Application for managing customer installations across environments, covering configuration, feature flags, and i18n
• Creating and maintaining a custom Design System built on Material UI, used across the full product
• Setting up and maintaining CI/CD pipeline and full QA suite (linting, unit, integration, and e2e testing)
• Architecting and implementing a multi-environment release process using Helm and Helmfile; owning infrastructure as code across AWS and Azure
• Researching and piloting new tools and frameworks; making build-vs-buy decisions to balance velocity, cost, and long-term maintainability
• Grew the engineering team from 4 to 10+ engineers, mentoring engineers and building a culture of ownership, code review and iterative delivery

Technologies: TypeScript, JavaScript, React, Node.js, Fastify, GraphQL, GraphQL Codegen, GraphQL Mesh, GraphQL Yoga, Hasura, Apollo Client, REST, CubeJS, PostgreSQL, Prisma, Elasticsearch, Meilisearch, Typesense, Kafka, Avro, Karapace, Kubernetes, Docker, Terraform, OpenTofu, Helm, Helmfile, GitLab CI, Keycloak, Better-Auth, OpenFGA, Nx, Vite, Vitest, Playwright, Testing Library, Storybook, Chromatic, Material UI, shadcn/ui, Tailwind, React Flow, recharts, i18next, Backstage, Grafana, Sentry, Zod, Claude Code, Codex, Mastra, Vercel AI SDK, Vercel AI Elements, AWS, Azure

• Implementing and extending an Electron app based on TypeScript, React and Node.js to display stream content and technical data
• Extending a Kotlin backend for message processing via Kafka
• Extending various React modules
• Programming custom solutions for customers, including testing
• Creating documentation
• Development in accordance with Scrum processes

Used skills: React, React Hooks, Jest, Vitest, Typescript, Electron, IntelliJ, Vite, Github, Jira, Node.js, yarn, npm, pnpm, Swagger, OpenAPI, Storybook, Docker, Prettier, Eslint, tailwindcss, i18n, GraphQL, CoPilot, Postgres, JSON, Sqlite, trpc, influxdb, Java, Spring, Kotlin, Kafka, Git, Sonarcube

Independent, part-time open-source engineering focused on build-time tooling for Next.js, React, MDX, and JavaScript/TypeScript compiler pipelines.

• Built next-slug-splitter to optimize content-driven Next.js applications. It analyzes MDX content at build time, resolves component usage, and generates route-specific handlers so pages avoid sharing the full catch-all component bundle.

• Created supporting plugins and utilities for scoped MDX transformations, nested component dependency resolution, compile-time refinement, safe ESTree evaluation, and object-graph diffing.

• Own architecture, API design, implementation, automated testing, npm publishing, documentation, demos, and performance benchmarking.

Building blocks:

• remark-scoped-mdx: Context-aware AST transformations with nested scope isolation, typed component registries, and prop inference.

• recma-component-resolver: Dependency-graph analysis and selective component forwarding across nested MDX includes.

• recma-static-refiner: Build-time prop extraction, schema validation, derivation, and pruning.

• estree-util-to-static-value and object-graph-delta: Safe static evaluation and deterministic, cycle-safe structural diffing.

Tech Stack:

• Frameworks: TypeScript · Next.js · React · MDX

• Compiler tooling: Unified · Remark · Recma · MDAST · ESTree · ts-morph · esbuild

• Competencies: Static analysis · AST traversal and transformation · dependency graphs · code generation · schema validation · route and bundle splitting

• Tooling: Vitest · tsup · npm · performance benchmarking

Consulting and software for intralogistics automation (AGV/FTS) · Product lines AGVHub (independent AGV project consulting, layout editor) and OneBob (all-in-one business software for small teams)

• Designed and planned the implementation of a supervisory control system for a bakery production line (engineering customer, kick-off workshop 08/2025): three development stages, eight acceptance-ready milestones, batch traceability, AGV integration with RFID, Vue frontend.
• Discovery and requirements discussions with plant logistics and IT teams at industrial customers (life science, aviation, steel, engineering): translated supervisory control, ERP interface, and VDA 5050 requirements into architecture and requirements specification structures.
• Go-to-market automation and analytics: Bing and Meta campaigns, LLM-supported LinkedIn content pipeline, performance dashboards for partners and sales.
• Expert posts on LinkedIn about robotics and intralogistics: around 170,000 impressions across 41 posts (03 to 08/2026).

• Development of automated software tests (unit, integration, regression and end-to-end tests).
• Applied technologies: Playwright, Vitest, JavaScript, TypeScript, Vue3, Go, Laravel, REST API, CI/CD, Docker, Git, GitHub, Scrum, Jira.

• Development and optimization of the RTL+ frontend application for SmartTV and set-top box platforms with React and Next.js.
• Key role in the technical coordination of developers within the team and in coordinating implementation.
• Central interface to adjacent teams to simplify development processes and improve cross-team alignment.
• Improved frontend performance, stability, and rendering behavior on low-powered devices in a restricted runtime environment.
• Implemented a frontend testing strategy with Jest, React Testing Library, and Playwright.
• Implemented accessibility improvements according to WCAG 2.2 and WAI-ARIA.
• Integrated Didomi Consent Management as a contribution to increasing ad monetization on streaming platforms.
• Used AI-supported engineering workflows with Cursor for structured implementation, refactoring, and faster problem solving.

Technologies used: React, Next.js, TypeScript, JavaScript, GraphQL, Apollo Gateway, Zustand, Tailwind CSS, Styled Components, React Testing Library, Playwright, Jest, HTML5, CSS3, AWS Lambda, EC2, CloudFront, S3, GitLab CI/CD, NX, Cursor

• Self-hosted table tennis equipment platform.
• Development of a custom “Racket Builder” that uses a co-evolutionary genetic algorithm to identify, evaluate, and recommend the optimal combinations of racket blades and rubbers based on physics heuristics and player data within a search space of over 4 billion combinations.
• Development of a custom fully automated web crawler to capture equipment specifications, integrating an automated pipeline for image normalization as well as data harmonization via DeepSeek.
• Cloudflare Edge Workers written in Rust to perform low-latency data searches and offload computationally intensive simulations from the main server.
• High performance and accessibility standards across a large Nuxt 4 codebase achieving 95–100/100/100 Lighthouse scores.

• SPA for automated communication of medical findings with role-based access (Sanctum)
• Server-side LLM integration (OpenRouter) with structured processing
• Automated sending via SMS/voice call (Twilio, ElevenLabs) with queue + status retry
• Full test coverage with 80+ documented test cases

Technologies: PHP, Laravel, LLM API (OpenRouter), Twilio, ElevenLabs, Laravel Sanctum, PHPUnit, Playwright, Docker, REST

Co-founded a software agency building custom web and cross-platform products. I owned the technical decisions across the whole portfolio and led 12 people, while carrying delivery planning, process and client relationships for 11 clients across 3 industries.

• Technical leadership: owned the technical decisions for the codebase across every project — stack, architecture, code conventions and the tooling the team worked with — and led the developers on how work got built through code reviews, pair programming and mentoring across a team ranging from junior to senior, keeping the codebase coherent as the portfolio and the team grew

• Delivery planning against the financial plan: built the company's financial plan and derived from it the billable hours each developer had to reach per month and the hours each project could absorb to stay within budget; planned capacity and scope against those figures and negotiated budgets and delivery dates directly with clients

• Client ownership: technical contact across the portfolio — requirements gathering and prioritisation, scoping and estimates, timeline communication, budget negotiation, and consistent transparency throughout delivery

• Team and people: owned the hiring and interview process end to end and took responsibility for offboarding where it was needed; designed an onboarding that got new developers productive within 1–2 days; cleared blockers daily and kept a close eye on where effort was creating value and where it was not

• Process ownership: consolidated a micro-service landscape spread over 15+ repositories into a single monorepo, cutting backend development time by ~40% and simplifying releases for 6 engineers; set up deployment pipelines with GitHub Actions and GitLab CI; ran retrospectives and turned the feedback into concrete changes; introduced AI agents into day-to-day development

• Delivered short-staffed: when the team shrank from 8 developers to 2, restructured scope, introduced AI-assisted development to hold the schedule and took on Go backend work alongside my own frontend scope

• Architecture and code: defined the architecture for every project in the portfolio — the structure the rest of the team built within — and wrote roughly 90% of the frontend code myself, from SSR applications with Next.js and Remix to cross-platform apps with Capacitor

• From zero to production: took a practice management platform — administration, inventory, integrated online shop, chat messenger — from an empty repository to production. Live in 7 markets with at least 7 more coming up, serving tens of thousands of users

• Delivery under pressure: built and shipped a replacement online shop for a Fortune 250 client in 4 days, restoring order intake while their global shops had been offline for several weeks

• Design system: built a cross-project design system used across 7 products, so new projects and features started from a shared, consistent base

• Cross-platform and real-time: built iOS and Android apps with Capacitor for a client live event with 1,000+ participants — web sockets and push notifications for real-time content, Stripe payments supporting PayPal, Apple Pay, Google Pay and cards

Key technologies: React, TypeScript, Next.js, Remix, GraphQL, ConnectRPC, Redux, Zustand, Go, Node.js, Turborepo, Nx, Capacitor, Ionic, WebSockets, Stripe, PostgreSQL, Playwright, Cypress, Vitest, Storybook, GitHub Actions, GitLab CI, Claude Code, Cursor, GitHub Copilot

• Senior software engineer focused on React, TypeScript and AI-assisted product workflows
• Build frontend systems for complex SaaS products, internal tools and operational workflows
• Recent work includes AI evaluation tooling, support reliability analysis and developer-focused QA systems
• Available for freelance and contract engagements, especially remote-first projects

• Developed a new iOS access-control scanning app for security/gate staff to validate RFID wristbands/badges in real time
• Implemented an online/offline hybrid architecture: scans are first checked against the API, with a fallback to local SQLite data in case of network issues, including complete access policy evaluation (zone, direction, scan limits)
• Developed a native iOS RFID bridge: connected the proprietary RFID SDK (QuantumSDK) via a custom Expo Config Plugin + Native Module; integrated LineaPro Bluetooth scanner hardware
• Implemented real-time updates via WebSocket (Pusher protocol), including private-channel authentication and reconnect with exponential backoff for device-/gate-/event-based configuration changes
• Designed a 3-level persistence setup (Keychain/MMKV/SQLite) for secure credentials, high-performance state and offline-capable scan/credential data
• Implemented incremental credential sync (Cursor + updated_after) as well as batch upload of scan logs after reconnect to ensure consistent data in field operations