Senior Fullstack Engineer

About the role

About the Role We're a fast-growing, angel-funded European AI SaaS startup building a German-language AI phone assistant used by thousands of businesses across Europe. Our small, high-ownership engineering team works in a remote-first environment, and we're looking for a Senior Fullstack Engineer to take end-to-end responsibility for building product features that deliver real, measurable value to customers. You'll work at the intersection of product and engineering — owning features from first idea through architecture, implementation, and release. Native-level German proficiency is required for this role, as our product and customers are primarily German-speaking. What You'll Do Own features end-to-end: from idea and prototype through architecture, implementation, and production release. Engage directly and continuously with customers, partners, and Sales to surface real pain points and turn them into product improvements. Run product discovery by forming hypotheses and validating them with lightweight, quick experiments before committing to large builds. Instrument your features and gather the metrics needed to enable data-driven product decisions. Build pragmatic, scalable software that balances immediate customer value with long-term maintainability. Communicate asynchronously wherever possible and prioritize shipping over excessive meetings. Act with radical ownership — push initiatives forward without waiting for permission. Work remotely with CET overlap, with the option to work from the Vienna office as needed. What We're Looking For Must-haves (dealbreakers): 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 language proficiency. Required: Experience with product discovery: forming hypotheses and validating them quickly through experiments. Proven ability to identify, collect, and use metrics to support data-driven decisions. Track record of collaborating with customers, partners, and sales teams to understand pain points and define value. Experience owning architecture decisions through to production release for customer-facing applications. Nice to have: Experience integrating LLMs (e.g., OpenAI) into software applications — a major plus . Experience deploying AI-enabled services on Microsoft Azure in Europe. Familiarity with GDPR and EU AI Act considerations for AI services. Prior experience in a high-growth startup environment. Compensation & Benefits Salary range: $80,000 – $120,000 USD annually Remote-first work environment with CET overlap High autonomy and direct impact on product direction Work with a lean, high-calibre team on cutting-edge AI technology Visa sponsorship is not available for this role. Location Fully remote (CET overlap preferred). Optional access to the Vienna, Austria office. Candidates based in Austria or Germany are particularly well-positioned.