Fullstack Developer

• Build and refactor features end-to-end, across interfaces, production tooling, and consumer-facing apps

• Develop and integrate REST and GraphQL APIs — both sides of the contract

• Create responsive, polished frontends that translate design intent into production UI

• Work with Docker as part of normal development and deployment

• Make architectural and product decisions, not just implement them

• Collaborate closely with backend, frontend, design, and hardware teammates

• Continuously raise the quality bar: performance, testing, and code health on both sides of the stack

• Own product and platform flows end-to-end: design, build, ship, operate, and improve. Not "frontend with backend tickets," and not "backend with React on the side." Real ownership across both sides of the API

• Drive architectural decisions that span the stack: where logic lives, how data flows, how systems stay coherent as they grow

• Operate production systems. Debug across browser, API, queue, database, and infrastructure, and improve observability so the next person doesn't have to start from scratch

• Lead on performance and scalability on both sides: frontend render performance, bundle and asset strategy, backend query and queue performance, caching, async processing

• Apply real security awareness across the stack: authentication and authorization done correctly, common exploits avoided by design (injection, SSRF, broken access control, XSS, CSRF), and dependency hygiene

• Navigate the everyday tradeoff between shipping fast and building sustainable systems, and explain your reasoning to people who aren't engineers

• Collaborate directly with hardware engineers on production-side workflows, and with operations on scanning and consumer-facing flows

• Mentor other engineers and help establish the practices (reviews, testing, deployment, on-call) that scale with the team

• Senior-level experience as a full-stack engineer who has genuinely owned both sides. Not a frontend dev with backend tickets, not a backend dev who occasionally touches React

• Strong React, TypeScript, and Next.js on the frontend; strong Node.js fundamentals

• Demonstrated architectural judgment across the stack: knowing where to put logic, when to introduce abstractions, when to extract a service

• Production operations experience: debugging real incidents end-to-end across browser, API, queue, database, and infrastructure

• Performance and scalability work on both sides, on systems with real load

• Security awareness beyond basic auth. You understand the common attack surface and design to avoid it

• Comfort with ambiguity and the ability to drive technical direction independently

Big advantage

• Laravel, Laravel Nova, and PHP — this is our primary backend stack, and full-stack here genuinely means full-stack

• Tailwind CSS

• Docker as part of normal development and deployment

• Solid relational database work (MySQL); exposure to non-relational stores (MongoDB, InfluxDB) is a plus

Background

We care about what you can do, not where you learned it. Formal CS background, 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.