Staff Machine Learning Engineer (AI)

Location: San Francisco, United States; hybrid with 3 days per week in the office

Salary: $265,000–$280,000 base salary plus equity

Company

hirify.global is a specialist recruitment partner connecting AI, machine learning, data, and engineering talent with technology companies.

What you will do

• Design and build reinforcement learning environments for agentic tasks, including task definitions, tool interfaces, state management, reward structures, and evaluation logic.
• Build systems for large-scale agent trajectories, parallel experiments, model evaluation, verifiers, graders, and rubrics.
• Develop supervised fine-tuning and reinforcement learning post-training pipelines.
• Run experiments and diagnose model behavior, training performance, reward quality, and data quality.
• Develop production-grade ML infrastructure covering orchestration, reliability, fault tolerance, and experiment management.
• Translate ambiguous technical problems into architectures and execution plans while providing hands-on technical direction to engineers.

Requirements

• Strong hands-on Machine Learning Engineering experience beyond model deployment or API integration.
• Practical experience with model fine-tuning or post-training, including exposure to supervised fine-tuning and reinforcement learning or preference-optimization techniques such as GRPO, PPO, DPO, or similar.
• Experience with agentic systems, model evaluation, training environments, reward design, or related areas, with an understanding of how to assess model improvement and diagnose unsuccessful training runs.
• Strong Python skills and production software engineering fundamentals.
• Experience with system design, distributed systems, ML infrastructure, platform engineering, or data systems.
• Strong architectural judgment, difficult technical decision-making, and the ability to provide technical direction without formal management authority.
• High agency, independent problem identification, and a track record of driving work to completion.
• Comfort working in ambiguous, rapidly changing environments and collaborating with highly technical stakeholders.

Nice to have

• Strong understanding of modern model training, evaluation, and agent development.
• Ability to operate at Staff level by setting technical direction rather than only executing predefined requirements.
• Comfort moving between experimentation, infrastructure, architecture, and implementation.
• A builder mindset rather than a purely academic or publication-oriented background.
• Comfort using AI coding tools while understanding and defending the resulting implementation.

Culture & Benefits

• Permanent hybrid role with 3 days per week in the San Francisco office.
• Work on reinforcement learning, agent training, post-training, evaluation, and technically challenging AI systems.
• Combine deep ML problems with production engineering responsibility and meaningful technical ownership.
• Work across fast-moving AI problems in an environment valuing speed, high agency, engineering judgment, and individual impact.
• Base salary of $265,000–$280,000 plus equity.