Research / Data Engineer - Post-Training & RL

Researcher or engineer? This role wants both, in one person. A profitable, seed-stage AI company in San Francisco creates long-horizon reinforcement learning environments and post-training data for leading AI labs in the US and abroad. Most data providers solve demand by adding people. This team treats post-training data as a research problem and scales it with processes that improve themselves. Demand for their data is bigger than what they can deliver today, so they're growing a small, very strong core team of researchers and engineers. What you'll own The full post-training loop: infrastructure, training runs and the data that goes into them Long-horizon RL environments and tasks in many fields, from science to ML research itself Scaling data generation through smarter, self-improving tooling, not more headcount Judging which real-world tasks are worth building, because they matter to the labs and the economy What you bring Real depth in ML research (think post-training, RL, evals or interpretability) and serious engineering skills You've post-trained models yourself and built the datasets for it A good eye for data, or the research ability to build that eye fast You read code fast and solve problems quickly in PyTorch and ML pipelines Curiosity that shows: papers, side projects, open source contributions or writing Roughly 3–7 years of experience Bonus points Both published research and things you actually shipped Domain depth next to ML, such as neuroscience, physics, chemistry or systems Artefacts people use: fast libraries, benchmarks or well-cited papers What's in it for you $250k–$300k base Work that goes straight into how frontier models are trained A small, senior team where research and engineering are one job Open to visa holders as well as US citizens and green card holders Good to know Full-time, on-site in San Francisco, 9-9-6 Process: first call with a founder - technical interview (a standalone problem, with an ML version in PyTorch) - work trial - offer #J-18808-Ljbffr Rnb Consultancy