Senior Research Engineer

Role : Senior Research Engineer

Employment Type : Full-time

Location : On-site, San Francisco (5 days / week, no remote option)

Compensation : $200,000 - $275,000 base salary + 0.5-2% equity

About the Company

This YC-backed startup is focused on post-training data and reinforcement learning (RL) environments for foundation model labs and applied AI companies. The company has raised ~$3.6M from top-tier venture capital firms and is experiencing rapid growth (200%+ month-over-month). With a small, research-focused team, they are building scalable data and RL infrastructure to power next-generation AI development.

The Role

The Senior Research Engineer will be responsible for designing scalable RL recipes, building modular environments, and driving research at the intersection of infrastructure and reinforcement learning. This role includes working on both internal and customer-facing projects, with opportunities to publish foundational research, open-source environments, and training data.

The position requires a balance of hands-on implementation, research innovation, and collaboration with product teams to create user-friendly interfaces for data generation and evaluation.

Key Responsibilities

• Design and implement scalable RL recipes for task-specific post-training models.
• Develop modular environments, reward functions, and evaluator scaffolds.
• Build data generation and curation pipelines to support post-training workflows.
• Conduct foundational research and contribute to open-source publications.
• Collaborate with product teams to create accessible tools for non-technical users.
• Advance research bridging scalable infrastructure and modern RL frameworks.

Candidate Requirements

Tech Stack

Python, PyTorch, reinforcement learning frameworks.

Culture & Opportunity

Benefits & Perks