Founding Engineer - LLM Infra & Platform

Company Pax Historia is creating the future of interactive entertainment. We’re building the platform for worldbuilders, storytellers, and game devs to create and publish any ‘what if’ they can think of. So far, most of the 25k+ user published presets on our site are historical (eg, ‘what if Rome never fell?’), but fantasy and sci fi are the fastest growing categories on the site. We have seen over 92 million rounds played and raised a 10M+ seed round in March. We’re backed by Y Combinator (W26), Bessemer, Pace Capital, Z Fellows, and more. Role Every game on Pax Historia depends on our ability to send huge numbers of requests across many AI providers and get the right response back quickly, reliably, and cheaply. We’re hiring an engineer to own that system. You’ll work on provider reliability, structured outputs, caching, routing, and monitoring. At the end of the day, you will need to: - Ensure that the 37+ models on our site reliably handle our ~240 billion weekly tokens. - Reduce costs and latency for our 60k+ daily active users wherever possible. You will not be in charge of model-training. We do not run model inference ourselves. If you’re obsessed with detail, data oriented, and have a strong tendency to verify everything, then this might be a great fit for you. We don’t expect you to have done this exact job before, but we are expecting you to be a fast learner with extremely strong fundamentals. Logistics You’ll be our 7th team member. We work in-person in San Francisco, 5+ days/week. We are open to sponsoring visas. Comp will include meaningful equity to reflect your responsibility as a founding engineer.