Sr. Model Engineer, RL Training Framework (AI)

Location: Palo Alto, CA, United States

Salary: $180,000–$400,000 USD per year

Company

xAI is building a superintelligence stack spanning Colossus supercomputers, Grok models, and applications including Grok Bot, Grok Build, Grok Imagine, Grok Voice, and X.

What you will do

• Design and implement systems supporting RL workloads from small-scale ablations through production training runs.
• Profile, debug, and optimize end-to-end training performance.
• Improve the scalability and observability of the RL stack.

Requirements

• Write production-quality code in Python, PyTorch, JAX, Rust, or C++.
• Train large models, including pre-training, post-training, fine-tuning, or RL training of neural networks with 1B+ parameters.

Nice to have

• Experience building, debugging, and optimizing large-scale distributed systems.
• Experience with large-scale LLM training infrastructure.
• Experience with RL numerics.
• Strong knowledge of reinforcement learning techniques.
• Ability to work in unfamiliar areas and solve problems across the stack.

Culture & Benefits

• Equity is included as part of the total rewards package.
• Comprehensive medical, vision, and dental coverage.
• Access to a 401(k) retirement plan, short- and long-term disability insurance, and life insurance.
• Additional discounts and perks.
• Equal opportunity employment.