Founding Engineer - Full Stack

About the Role A fast-moving, Y Combinator–backed AI martech startup is looking for a Founding Engineer — Full Stack to join a tiny founding team at the cutting edge of AI brand intelligence. You'll help build the systems that let brands understand and influence how large language models perceive, discuss, and recommend their products — a genuinely novel problem space sitting at the intersection of AI research, product, and engineering. This is a high-ownership, zero-fluff role. You'll work directly alongside founders, stay close to customers, and ship end-to-end features in a fast-paced startup environment. You'll also help define what great engineering looks like for a team that builds with AI agents every day. What You'll Do Own problems end-to-end — from high-level customer insight all the way through research and infrastructure. Maintain a tight feedback loop with customers and the leadership team; move fast and ship. Help shape the engineering culture and practices of a brand-new team. Continuously reinvent patterns and best practices for working alongside AI agents as collaborative teammates. What We're Looking For Must-haves: 1+ years of experience on software engineering teams (2+ preferred), including at least one stint of 18+ months in a strong startup or scale-up environment. Full-stack comfort: customer-facing UI (React) through to backend services (Python) and cloud infrastructure (Terraform, AWS). Hands-on experience building agentic systems — domain-specific systems that shape or influence model behavior. Strong product instincts and ability to translate customer needs directly into shipped features. Eagerness to adopt AI-powered coding tools and adapt to rapidly evolving engineering tooling. US work authorization required (US citizen or valid US work visa); no visa sponsorship available. Nice-to-haves: Startup experience or notable self-driven personal projects that demonstrate high agency. Experience talking to customers directly and incorporating feedback into product decisions. Curiosity about how LLMs work and interest in applied AI interpretability. Scientific research background in AI, ML, or a related domain. Compensation & Benefits Salary: $170,000 – $250,000 USD annually, depending on experience. Early-stage equity commensurate with a founding-team role. Location This is an on-site role based in Los Angeles, CA . Candidates in other major US hubs may be considered, but on-site presence is expected.