Senior Research Engineer, LLM Training & Post-Training - Lightning AI

Lightning AI is seeking a Senior Research Engineer to advance LLM training, post-training, evaluation, and deployment across its platform and customer workloads. The role involves building and optimizing PyTorch-based training infrastructure, improving model quality via methods like SFT, RLHF, DPO, PPO, and GRPO, and collaborating with research, infrastructure, and customers. This role is hybrid with a minimum of 2 in-office days per week in San Francisco, Seattle, NYC, or London, with fully remote work considered for candidates outside those hubs.

• Design, build, and optimize training and post-training pipelines for large language models.
• Improve model quality through supervised fine-tuning, continued pretraining, preference optimization, reinforcement learning, evaluation, and experimentation.
• Build and improve PyTorch-based training infrastructure, tooling, and developer workflows.
• Optimize distributed training across multi-GPU environments by improving throughput, memory efficiency, scalability, and GPU utilization.
• Investigate challenging model training issues, including convergence, instability, communication overhead, and performance bottlenecks.
• Design evaluation methodologies, benchmark models, analyze failure modes, and guide model improvements through experimentation.
• Collaborate directly with customers to understand real-world workloads and translate those learnings into improvements across Lightning AI's research platform.
• Partner closely with research, infrastructure, and platform engineering teams to build production-ready AI systems.