Senior Software Engineer

Senior / Staff Backend & Platform Engineer - Early-stage AI startup (San Francisco / Bay Area - hybrid)

The company

A small, well-funded AI infrastructure startup in San Francisco, backed by some of the best investors in the Valley. We build the core platform and data infrastructure underneath an AI product that's used right across whole organisations and it's already in the hands of real customers. You'd join as one of the early engineers, with unusually direct ownership over what gets built and how.

What you'll do

• Design, build and ship scalable backend and platform systems from the ground up
• Build the data and agent infrastructure that lets LLMs reason over large, messy, real-world datasets
• Own the architecture
• Move fast in an early-stage environment where you're trusted to make the calls

Who we're looking for

We're after a seasoned platform engineer, someone who's built serious data infrastructure at scale and wants to do the defining early work at a company this size.

• 3+ years building backend and data-platform systems, including time at companies operating at genuinely massive data scale
• Has led a data or ML platform, owning the architecture and long-term direction, not just implementing tickets
• Deep data-infrastructure chops: data architecture, storage and execution engines, lakehouse-style migrations, and internal tooling/DSLs that make ML experimentation faster and cheaper
• Strong in Python and cloud infra; fluent with databases, data modelling and API design
• Bonus: hands‑on with LLMs, agentic frameworks or RAG

Why it's worth a look

• Founding-level ownership and influence at a genuinely early stage
• Competitive salary and meaningful equity
• Full health cover (medical, dental, vision), wellness/fitness membership, transport stipend, meals on office days
• Flexible time off; SF-based with hybrid flexibility