Senior AI Infrastructure Engineer (Founding Hire)

This is the first engineering hire at an early-stage AI infrastructure startup that has a working product, live revenue, and a clear mandate: rebuild what works into agentic infrastructure that can serve a million users. You will work directly with the founder, owning architecture and technical direction with no engineering organisation above you, and the expectation is that this becomes a CTO seat as the team grows.

What You'll Do

• Redesign and scale a working agentic system into production infrastructure capable of handling significant user load.

• Design and operate the agent runtime, covering orchestration, memory, verification, and the reliability machinery that makes an AI workforce trustworthy.

• Own work end to end across backend, infrastructure, frontend, and agent layers.

• Set the technical stack, engineering bar, and team norms as the person who is defining them.

• Ship to real business customers on a weekly cadence.

What We're Looking For

• At least 2 years shipping production software, or an equivalent record of building and launching real systems as a founder or solo builder; strong younger engineers are explicitly in scope.

• Demonstrated experience building and running LLM or AI agent systems in production with real users depending on them, not demos or side projects.

• Full-stack range: able to take work from backend and infrastructure through to the UI without waiting for a specialist.

• Proven ability to turn a working prototype into infrastructure that holds real load, including architecture, data modelling, runtime, and orchestration.

• Track record of owning technical decisions with no engineering hierarchy above you, as a founder, early hire, or solo technical lead.

• Founder instincts: ex-founders or co-founders are a strong signal.

• Experience with agent orchestration, agent memory, evals, verification systems, or multi-agent workflows is a strong plus.

• Familiarity with recruiting, agency, or service-delivery businesses is a bonus given the active verticals.

• Strong CS fundamentals, whether from a university background or a well-regarded engineering environment, are a welcome signal but never a requirement.

• Based in Europe and genuinely open to relocating to San Francisco within the first year.