Senior Software Engineer

Founding Member of Technical Staff — RL Environments & Platform EngineeringWe're partnering with a fast-growing, well-funded AI startup building the training and evaluation infrastructure that powers frontier model development. Their RL environments are used to teach and test the world's most advanced AI systems on increasingly realistic, long-horizon, high-difficulty tasks — spanning financial services and beyond.They're hiring their first wave of Founding Members of Technical Staff to own platform engineering, build next-generation RL environments, and shape the engineering org from day one. This is a rare opportunity to define both the technical foundation and the culture of a company at a genuine inflection point.What you'll doBuild the RL environment training/inference infrastructure that supports customer usage at scaleResearch and develop next-generation RL environments that are increasingly realistic, long-horizon, and difficult for frontier modelsBuild software to 10–100x the quality and throughput of RL environment creationInnovate on synthetic data pipelines to generate realistic, high-fidelity problemsCreate platform analytics tracking environment costs, hours, bottlenecks, and subject matter expert (SME) managementCraft domain-specific verifiers for financial services verticals and beyond (e.g., verifiable rewards for PowerPoint building, Excel modeling, quantitative trading)Help establish engineering culture and practices from the groundWhat you bringExperience building evaluations, benchmarks, or RL systems for AI agentsStartup speed — you iterate fast, ask questions fast, respond fast, and aren't afraid to make (and fix) mistakes fastStrong product/user ownership and the judgment to prioritize across a large, ambiguous roadmapComfort being client-facing — talking directly to users, customers, and subject matter expertsNice to haveA research background (e.g., training models, publishing papers)Experience as a founder or early employee at an early-stage startup