Staff ML Engineer - Open-Models & RL Systems

reflectionai; San Francisco, New York (CA, NY); On-site; USD 180,000 - 300,000; Full time

Benefits offered by this job

Top-tier compensation

Stock options

Health & wellness

Meals provided in office

Parental leave

Unlimited vacation (US)

Visa sponsorship where applicable

Team building

Job summary

Reflection AI in San Francisco is building open foundational models and scalable systems to advance intelligent agents. We are seeking a seasoned AI/ML engineer to transform pre-trained models into aligned, general agents and to push the frontier of post-training with data curation and large-scale optimization.

You will collaborate across research and infrastructure, own ambitious agendas, and help shape the future of open intelligence through concrete experiments and robust implementation.

Qualifications

• Deep understanding of machine learning fundamentals and practical experience with large-scale LLM training.
• Strong engineering skills with complex ML codebases and distributed systems.
• Experience improving model behavior through data, reward modeling, or RL techniques.
• Evidence of owning ambitious research or engineering agendas leading to measurable model improvements.
• Thrive in a fast-paced startup environment with action and clarity of execution.

Responsibilities

• Build systems that transform powerful pre-trained models into aligned and general agents.
• Drive research and engineering initiatives from data curation to large-scale optimization.
• Develop data generation pipelines, reward models, reinforcement learning algorithms, and inference-time scaling techniques.
• Collaborate across pre-training and post-training teams to deliver step-function gains in model capability.
• Contribute to understanding how large models learn to reason, follow instructions, and improve through reinforcement learning.

Skills

Machine learning fundamentals

LLM training

Distributed systems

Data generation / reward modeling

Research leadership

Job description

Reflection AI in San Francisco is building open foundational models and scalable systems to advance intelligent agents. We are seeking a seasoned AI/ML engineer to transform pre-trained models into aligned, general agents and to push the frontier of post-training with data curation and large-scale optimization.

You will collaborate across research and infrastructure, own ambitious agendas, and help shape the future of open intelligence through concrete experiments and robust implementation.