Frontend Developer

You’ll be part of a small team of software developers building the factory of tomorrow. Your job will be to refactor and optimize existing software and the development of new tools and services from footscan via production to the consumer. As a part of our development team, you will find solutions for problems you never heard of and extend your knowledge daily.

• Drive frontend architecture across our three product surfaces, making decisions about patterns, boundaries, and shared infrastructure that hold up over time

• Own features end-to-end: from the design conversation through implementation, production rollout, and the inevitable debugging session when something behaves differently on the factory floor than it did in staging

• Lead on performance, scalability, and observability. Core Web Vitals on the consumer side, realtime responsiveness on the hardware-adjacent side, and the instrumentation that lets us know which is broken

• Apply frontend security rigor. Not just "we use auth tokens," but a working understanding of XSS, CSRF, CSP, dependency risk, and the everyday vulnerabilities that ship to production when nobody's watching

• Navigate ambiguity: translate vague product, hardware, or operational needs into technical direction, and know when to ship a fast solution versus invest in a durable one

• Collaborate directly with hardware engineers on the production-side UIs and with operations on scanning and in-store experiences. The feedback loop is short and the requirements are real

• Mentor other frontend developers, review code with intent, and help establish the engineering practices that scale with the team

• Senior-level React and TypeScript experience, with a track record of owning non-trivial frontend systems in production

• Demonstrated ability to make architectural decisions about patterns, abstractions, and where to draw the line between shared and bespoke

• Production debugging experience across the full path: browser, API contract, network, and infrastructure. You've been the person who actually found the problem

• Performance and scalability work on real systems. Not just Lighthouse scores, but render performance, bundle discipline, data-fetching strategy, and caching

• Frontend security awareness beyond auth-token plumbing. You understand the common attack surface and how to avoid expanding it

• Comfort with ambiguity and the judgment to make decisions when requirements aren't fully formed

Nice to have

• Experience with realtime, hardware-adjacent, or kiosk/in-store frontends

• Manufacturing, production, or operational-tooling context

• 3D, WebGL, or product-visualization experience (Three.js, R3F)

• PWA and/or native (React Native, Capacitor) experience

• Background contributing to design systems or frontend platform work

Background

We care about what you can do, not where you learned it. Formal CS background, bootcamp, apprenticeship, serious open-source contributions, or a strong portfolio of shipped work, all valid signals.

At Zellerfeld, you will find a multidisciplinary team of engineers, SW and HW specialists, entrepreneurs, designers, and students with a common passion. We embrace contrarian thinking, humility, pushing limits, and improving ourselves. We utilize a flat hierarchy, and we want your voice to be heard. We also care about bonding because we want to be a tight-knit community, so be prepared to spend quality time with everyone, including the CEO!

As a company specializing in both hardware and software, we value close collaboration within our team. Therefore, we are seeking candidates who can join us at our office in Hamburg.