Member of Technical Staff - Research Engineer, RL Environments
Preference Model· Engineering
San Francisco$200k - $350k + equity + bonusFull-timePosted yesterday
About the role
Role designing and building reinforcement learning environments and reward functions for frontier ML models, blending research and engineering with ownership over environments from design to production, focusing on safely advancing model capabilities.
Responsibilities
- Design and build RL environments and reward functions that produce clean, learnable signals for frontier models on ML research and engineering tasks
- Build deep expertise across the frontier of ML research, training, and inference infrastructure
- Collaborate with others to brainstorm and create new ideas and tools to improve the environment building process
Qualifications
- 5+ years of experience working in machine learning or research, primarily on LLMs and transformer models
- Strong ML fundamentals and broad research interests with ability to translate topics into RLVR problems
- Proficiency in Python and systems programming and at least one of PyTorch or JAX
- Problem solvers who take ownership and drive solutions end-to-end
- Passion for staying current with the rapidly evolving ML infrastructure landscape
- Ability to meet throughput expectations and respond quickly to feedback
- Expert knowledge in an active DL/ML research area with publications or public code is a plus
- Research experience (PhD, MS) is a big plus
- Deep understanding of transformer internals, training/inference of modern LLMs, experience with inference libraries (e.g., vLLM, SGLang) is a plus
- Strong expertise in kernel development (CUDA, Triton, Pallas) is a plus
- Experience building complex interactive RL environments is a plus
Skills
Required:PythonPyTorch or JAXRL Environment DesignMachine Learning / Research
Benefits
- Competitive cash and equity compensation (>90th percentile)
- Ownership and autonomy in a fast moving startup environment
- Opportunity to work with top machine learning engineers
- Health, vision, dental, benefits
- 401K match
- Lunch provided everyday onsite
- Weekly snack orders
- Visa sponsorship & relocation support available
Last updated Oct 25, 2026. Interested? Apply on the company site.
About Preference Model
Preference Model is building the next generation of training data to power the future of AI.
Automated ML research engineeringLLMsRL environmentsbessemer-ai-infrastructure-2026frontier AIreinforcement-learning-platformstraining data
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