25.10.2026 aktualisiert
100 % verfügbar
Freelance Senior Frontend Developer | TypeScript, React, Next.js | AI-assisted Dev
Kerpen, Deutschland
Nur Remote
FachhochschulreifeÜber mich
Senior frontend engineer with 15+ years in TypeScript, React and Next.js. I own architecture, write clean, tested code and develop spec-driven with AI (Claude Code). Open for freelance contracts, fully remote, EU-wide and worldwide, resident in Bonn, Germany.
Skills
StorybookAI AgentsGitHub ActionsContentfulClean CodeHTMLJavaScriptUnit TestingBugfixingCSSNode.jsScrumSoftware ArchitectureE2e TestingNext.js
Frontend engineer with 15+ years of experience. Core stack: TypeScript, React, Next.js, plus solid HTML, CSS/SCSS and vanilla JavaScript.
Architecture
- Component-driven frontends and design systems (Material UI, Storybook)
- Monorepos (Turborepo, pnpm) and clear API contracts (GraphQL, REST)
- Data and forms with Apollo Client or TanStack Query and React Hook Form
- Gatsby, Eleventy, Contentful and legacy Typo3 frontends with a modern build setup (esbuild)
Quality
- Testing with Playwright, Cypress, React Testing Library and Jest
- ESLint, Prettier and GitHub Actions as guardrails
- UI components built to ARIA patterns
- Lighthouse performance raised from about 60 to 100 on a public website
AI-assisted development
- Spec-driven with Claude Code: AI challenges the concept, I write the spec and review every change
- CSS and visual details I do by hand
Collaboration
- Led frontend teams, mentored developers, run code reviews
- Quick start and clean handover (docs, tests, one commit per ticket)
- Close work with product, design and backend; Scrum
Erfahrung
Berufserfahrungmehr als 10 Jahre
Freelancer seit2026
Sprachen
DeutschMutterspracheEnglischverhandlungssicherSpanischGrundkenntnisse
Projekthistorie
Tech: Typo3 (backend side), Eleventy, Nunjucks, vanilla JavaScript, SCSS, esbuild, Playwright, ESLint, Stylelint, Prettier, GitLab, Claude Code
Freelance frontend developer for tibet.de, the main channel of a Hamburg non-profit, working in a small freelance team with a backend developer and a UI/UX designer. I took over the frontend of a 10+ year old Typo3 website.
- Build system: introduced Eleventy, Nunjucks, esbuild and SCSS. One minified JavaScript file and two CSS files replaced scattered scripts. The backend developer now copies only the changed files from dist and commits them.
- Event calendar: about 170 events across four months, with filters by category and location, collapsible month sections, bookmarkable filter URLs and a mobile card layout that I designed and built on my own initiative.
- Components: three dependency-free vanilla JS components (Filter.js, accordion.js, AccordionJumpTo), built to ARIA patterns and developed spec-driven with Claude Code.
- Quality: Playwright test suite that grew with the components, ESLint, Stylelint and Prettier.
- Modernization: legacy stylesheet split into component SCSS (about 3,500 to about 2,000 lines), dead code removed, jQuery phased out step by step.
Small tickets with this workflow took about a third of my up-front estimates.
Product Manager for the AI initiative (agentic RAG) behind Taxy Answers: stakeholder management, backlog and requirements, translating between product, design and engineering. While I was at Taxy.io, Answers grew to 3 paying whitelabel customers and passed 3 million answered questions.
I made planning and review meetings leaner by having leads prepare from their own perspective, which cut planning time by roughly 30% (my own estimate).
Tech and methods: Scrum, backlog management, stakeholder management, requirements engineering
Tech: React, Next.js, TypeScript, TanStack Query, React Hook Form, Material UI, Turborepo, pnpm, Cypress, Sentry, GitHub Actions
Frontend Chapter Lead for several products, from consumer tax declarations to Taxy Answers, a whitelabel AI chat for regulated domains such as tax law. I was hands-on in every product, but did not own a complete topic alone.
- Architecture: analyzed the existing codebase and defined the architecture for all following products: Material UI component library, TanStack Query, React Hook Form, Turborepo + pnpm monorepo.
- Taxy Answers: drove most frontend architecture decisions for the whitelabel chat frontend (brandable per client, SSO, source citations). Supported two more product teams.
- Quality: introduced shared coding standards, lint guardrails and Cypress E2E tests, which the QA team took over. Reviewed code across all products.
- Team: took the chapter (2 employees and 5 external developers) to a fully in-house team and hired a developer who is still with the company.