Senior Fullstack Engineer

About the Role This is a senior individual contributor role on a small, fast-moving engineering team building an AI-powered phone assistant for European SMEs. You'll own features end-to-end — from discovery and architecture through to release — and your work will have a direct, measurable impact on thousands of business customers. What You'll Do Take full ownership of product features from initial idea and prototype through architecture, implementation, and release. Engage regularly with customers, partners, and Sales to surface real pain points and turn them into product improvements. Run lightweight product discovery by forming hypotheses and validating them with quick experiments before building large systems. Instrument your work and gather the metrics needed to support data-driven decisions. Build pragmatic, scalable software that balances immediate customer value with long-term maintainability. Communicate asynchronously and prioritise shipping over excessive meetings. Act with radical ownership — push initiatives forward without waiting for direction. What We're Looking For 5+ years of experience as a fullstack engineer with end-to-end delivery responsibility for customer-facing web applications. Strong hands-on experience with Node.js, TypeScript, NestJS, and React . Native-level German proficiency — essential for supporting a German-language AI product. Fluent English for team and internal communication. Product mindset: you measure success by customer value, not lines of code. Proven experience with product discovery, hypothesis-driven experimentation, and metrics-based decision making. Track record of collaborating directly with customers, partners, or sales teams to define and validate product value. Strong CS fundamentals and sound judgment when trading off speed, quality, and effort. Experience integrating LLMs (e.g. OpenAI APIs) into production applications is a significant plus. Familiarity with GDPR or EU AI Act considerations for AI services is a plus. Experience deploying AI-enabled services on cloud infrastructure in Europe (e.g. Azure) is a plus. Prior experience in a high-growth startup environment is a plus. Compensation & Benefits Salary range: €80,000 – €120,000 per year. Visa sponsorship is not available. Location Fully remote, with a preference for candidates based in Germany or Austria (CET timezone overlap required). An office in Vienna, Austria is available for those who prefer it.