Mason AI — Founding AI Engineer

San Francisco, CA · On-site · Full-timeCompensation: $160,000–$200,000 + 0.5–2% equity

About the Company

Our client is a seed-stage startup building agentic AI for the built world: multimodal agents that review construction blueprints for buildability and code compliance, becoming domain experts on rules like accessibility and fire-safety codes. They are the technical leader in their space, and their mission is to make housing more affordable — one of the very few places in tech where an engineer works directly on the housing crisis. This is a founding-engineer seat on a tiny, high-ownership team.

Founded 2025 · 1–10 people · Industry: Property Tech

The Role

A deeply self-directed founding AI engineering role owning the full experiment loop to improve the accuracy of the client's multimodal blueprint-compliance agents. The work is heads-down and technical, with a small amount of weekly user contact — not a forward-deployed role.

What you'll be doing

• Spend the majority of your time improving the accuracy of the multimodal blueprint-compliance agents — building autoresearch, improving evals, and running sweeps on experimental features you design.
• Own the full experiment loop: generating ideas, implementing them, and rigorously analyzing results on the eval framework.
• Become a domain expert on the parts of the building code that matter (accessibility, wildland-urban interface, structural and fire safety).
• Wear hats as needed: computer-vision experiments, lightweight data engineering, internal tooling, and webapp improvements.
• Roughly two hours a week of user contact and product dogfooding.

Tech stack: Tech-stack agnostic; TypeScript across front-end and back-end. Modern AI coding tools used throughout.

Requirements

• Highly independent and self-unblocking; able to direct your own work with minimal oversight
• Fast-moving and prototype-oriented; you ship experiments quickly
• Strong evaluation discipline and genuine research taste for high-risk, high-reward work
• Either a strong software engineer eager to grow into ML/AI, or an ML/AI engineer who already prototypes fast
• Comfortable across the stack (TypeScript front-end and back-end)
• Genuinely motivated by the mission of making housing more affordable
• Able to work on-site in San Francisco full-time, ~55 hours/week with some weekend availability

Nice to Haves

• Experience at an autonomous-vehicle company, where rigorous evaluation is second nature
• Background in highly regulated applied-AI domains (e.g. medical or legal) where evaluation discipline is critical
• Climate-tech or other mission-driven startup experience
• Strong academic background
• Genuine curiosity for digesting dense technical and regulatory material (building codes, technical diagrams)

Why Join

• Work directly on the housing affordability crisis — a rare opportunity in tech
• Founding-engineer ownership with a meaningful equity stake
• Join the technical leader in its space, with a demo that gets strong engineers excited
• Strong comp plus full benefits: free lunch and dinner at the office, fully paid health insurance with $1,000+/yr employer HSA contributions, and commuter and wellness benefits

Details

• Location — San Francisco, CA
• Work policy — On-site, full-time; ~55 hrs/week with some weekend availability
• Compensation — $160,000–$200,000 + 0.5–2% equity
• Visa sponsorship — None available; relocation supported
• Employment type — Full-time