Principal Research Engineer, Model Training & Post-Training

Highlights

• Own end-to-end model improvement loop from data and training to production feedback.
• Ship models that are measurably better for users across capability and reliability.
• Drive architecture and optimization decisions across training and inference.

What they offer

• Meaningful equity component
• Robust medical, dental and vision options with HSA, FSA and DFSA contributions
• 401k matching program
• Flexible Time Off, 10 paid holidays, 5 days sick leave
• Parental, Medical and Family care leave
• Cell-phone, wellness and office setup stipends

Ideal candidate

Hands-on technical leader who has led large-scale model programs and balances research ambition with product pragmatism. You care about shipping measurably better, reliable models and making principled tradeoffs for user impact.

Requirements

• Experience leading, or serving as a principal contributor to, large-scale LLM, multimodal, or foundation-model training or post-training programs
• Deep experience with transformer-based models, hybrid architectures, modern deep-learning frameworks, and distributed training systems
• Strong practical experience with post-training and alignment methods such as SFT, RLHF, DPO, GRPO, RLAIF, reward modeling, preference optimization, tool-use fine-tuning, or related approaches
• Experience operating or partnering on large-scale training infrastructure, ideally including GPU clusters at the scale of 1,000+ GPUs
• Strong systems instincts around throughput, cost, reliability, observability, debugging, checkpointing, reproducibility, and fault tolerance
• Excellent judgment around data quality, evaluation design, model regressions, release readiness, and production model behavior
• Ability to balance research ambition with product pragmatism, user impact, and operational discipline
• Experience leading senior technical teams while continuing to contribute directly to technical decisions and implementation
• PhD in Computer Science, Machine Learning, Artificial Intelligence, or a related field, or equivalent practical experience