Senior Research Engineer, LLM Data

Location: San Francisco, CA Employment Type: Full-time On-site: 5 days/week in-person About the Role Our client is a research lab that provides post-training data and RL environments to foundation model labs and frontier applied AI companies. They have raised significant funding from top-tier VCs and are growing rapidly. As a Senior Research Engineer, you will drive cutting-edge research at the intersection of scalable infrastructure and modern reinforcement learning (RL) frameworks. This is an opportunity to join an early-stage team with high autonomy and direct exposure to projects that are used and validated in production by leading labs. Responsibilities Design and implement scalable RL recipes for post-training task-specific models. Develop modular environments, reward functions, and evaluator scaffolds for both internal and customer-facing tasks. Drive research to enable RL-as-a-service and publish open-source environments and training data. Build data generation and curation pipelines to support frontier post-training. Collaborate with product teams to deliver a user-friendly interface for non-technical users to generate data. Requirements 4-7 years of experience in an AI/LLM research capacity (excluding undergraduate experience). Master's or PhD in Computer Science or a related field. Comfortable with core tooling like PyTorch and modern post-training techniques. Experience with evaluations and reward engineering. Published in top journals (ICLR, NeurIPS, ICML, etc.). Benefits Salary: $200k - $275k (Based on quality and experience). Equity: 0.5% - 2%. Visa sponsorship is available. Due to the high volume of applications we anticipate, we regret that we are unable to provide individual feedback to all candidates. If you do not hear back from us within 4 weeks of your application, please assume that you have not been successful on this occasion. We genuinely appreciate your interest and wish you the best in your job search. Commitment to Equality and Accessibility: At MLabs, we are committed to offer equal opportunities to all candidates. We ensure no discrimination, accessible job adverts, and providing information in accessible formats. Our goal is to foster a diverse, inclusive workplace with equal opportunities for all. If you need any reasonable adjustments during any part of the hiring process or you would like to see the job-advert in an accessible format please let us know at the earliest opportunity by emailing human-resources@mlabs.city. MLabs Ltd collects and processes the personal information you provide such as your contact details, work history, resume, and other relevant data for recruitment purposes only. This information is managed securely in accordance with MLabs Ltd’s Privacy Policy and Information Security Policy, and in compliance with applicable data protection laws. Your data may be shared only with clients and trusted partners where necessary for recruitment purposes. You may request the deletion of your data or withdraw your consent at any time by contacting legal@mlabs.city.