Senior Fullstack Engineer

Role details

ABOUT THE ROLE This is a Senior Fullstack Engineer position at a fast-growing, seed-funded European AI voice technology startup serving thousands of SMEs. You will own features end-to-end, from prototype to production, and directly shape the product experience for a German-language AI phone assistant used across Europe. WHAT YOU'LL DO - Take full ownership of features across the entire stack, from architecture decisions through implementation and release. - Engage regularly with customers, partners, and the Sales team to identify real pain points and inform priorities. - Run product discovery by forming hypotheses and validating them quickly through lightweight experiments. - Instrument your areas of ownership with the metrics needed to make data-driven decisions. - Build pragmatic, scalable software that balances immediate customer value with long-term maintainability. - Communicate asynchronously and keep meeting overhead low, prioritizing shipping. - Act with radical ownership, pushing initiatives forward proactively. WHAT WE'RE LOOKING FOR - 5 or more years of fullstack engineering experience with end-to-end delivery responsibility for customer-facing web applications. - Strong hands-on experience with Node.js, TypeScript, NestJS, and React. - Proven ability to drive product discovery: forming hypotheses, running experiments, and measuring outcomes. - Experience identifying, collecting, and using metrics to support product decisions. - Comfort collaborating directly with customers, partners, and sales to extract actionable insights. - Native-level German proficiency (required, given the product's language focus). - Fluent English for team communication. - Strong CS fundamentals and sound judgment when trading off speed, quality, and effort. - Experience integrating LLMs (such as OpenAI APIs) into production applications is a strong plus. - Familiarity with GDPR and EU AI Act considerations for AI services is a plus. - Experience working in a high-growth startup environment is a plus. COMPENSATION & BENEFITS Salary range: 80,000 to 120,000 EUR annually. Visa sponsorship is not available for this role. LOCATION Fully remote, with a preference for candidates based in Germany or Austria and availability during Central European Time hours. Optional in-person collaboration from the Vienna, Austria office is available.