Sr. Model Engineer, Mid-training (AI)

Location: Palo Alto, California, United States

Salary: $180,000–$440,000 USD per year

Company

xAI is building a super-intelligence stack spanning large-scale compute, Grok models, and AI applications.

What you will do

• Scale synthetic coding data to trillions of tokens using large-scale Docker verification.
• Distill flagship-model intelligence into flash models through synthetic data generation.
• Optimize mid-training data mixtures to raise the ceiling for reinforcement learning.
• Engineer long-context data recipes.
• Develop robust and diverse evaluations for mid-training checkpoints.

Requirements

• Production-quality coding experience in Python, PyTorch, JAX, Rust, or C++.
• Experience training large neural-network models with 1B+ parameters through pre-training, post-training, fine-tuning, or reinforcement learning.

Nice to have

• Familiarity with scaling laws and large-model scaling.
• Strong ability to design machine-learning experiments.
• Experience curating AI training data for text, image, audio, and video modalities.
• Strong engineering skills with large-scale data-processing frameworks.
• Experience with Spark, Ray, or other large-scale data-processing frameworks.

Culture & Benefits

• Full-time role with base salary as part of a broader total-rewards package.
• Equity and comprehensive medical, vision, and dental coverage.
• 401(k) retirement plan, short- and long-term disability insurance, life insurance, discounts, and other perks.
• Equal opportunity employer.