About

Jonas Mattes — Freelance full-stack engineer, Cambridge

Jonas Mattes

A decade of shipping software — now in service of Cambridge teams that need to ship.

I'm a senior full-stack TypeScript engineer based in Cambridge. Over the last ten years I've written software inside some of the most demanding engineering organisations in the world; today I bring that experience to startups, small businesses, and research teams who need a senior pair of hands to get a product built and shipped.

I take on one or two engagements at a time so each gets the focus it needs. The work spans the whole arc and the whole stack — shaping the idea, building the product end-to-end from frontend to infrastructure, and integrating AI features that actually pull their weight rather than bolting an API call onto the side.

Experience

  1. Now

    Freelance full-stack engineer · Independent · Cambridge

    I partner with startups, small businesses, university spinouts, and research teams to take product ideas, stalled prototypes, and manual processes to production — design, build, and launch, with AI features built in where they earn their place. Most recently I rebuilt a German edtech platform from the ground up and took it 0→1, from prototype to pilot schools.

  2. Previously

    Software engineer · Google

    Built and shipped production software at Google scale, working across a large engineering organisation on systems used by millions. It set the bar for how I think about reliability, code quality, and shipping software that other engineers can maintain.

  3. Before that

    Software engineer & consultant · Zühlke

    Delivered software products for enterprise clients as part of a consulting team — including work for SBB, the Swiss national railway. Consulting taught me to drop into an unfamiliar domain, earn trust quickly, and ship something real against a real deadline.

  4. Early career

    Working student · BMW · Audi

    Cut my teeth as a working-student engineer at two of Germany's automotive giants while studying — my first taste of writing software inside large, demanding engineering organisations.

Toolkit

I work primarily in TypeScript across the stack, with a bias towards type-safety end-to-end so the codebase scales with the product and hands off cleanly to whoever comes next.

  • Frontend & UX

    • React
    • Next.js
    • Tailwind

  • Backend & APIs

    • Node.js
    • Hono
    • oRPC
    • tRPC

  • Data & databases

    • Postgres
    • Drizzle
    • Migrations

  • AI features

    • LLM APIs
    • Evals
    • Prompt tooling

  • Infrastructure

    • Kubernetes
    • Docker
    • Vercel
    • Self-hosting

  • CI/CD

    • GitHub Actions
    • Preview environments
    • Automated tests

  • Security & compliance

    • Encryption
    • Data residency
    • Auth

  • Performance

    • Core Web Vitals
    • Profiling
    • Caching

  • Accessibility

    • WCAG 2.2 AA
    • Semantic HTML

  • Product thinking

    • Discovery
    • Scoping
    • Roadmap

Want a senior engineer on your product?

I take on 1–2 projects at a time. Let's talk about yours.

Book a call →