Senior Fullstack Engineer

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.