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Principal Research Engineer, Post-Training

Redwood City, CA💼 Full-time🗓 2026-06-22 → 2026-09-25

Core

Lead technical vision and execution for post-training systems that transform foundation models into aligned, role-playing chat features for millions of users.

Role type

Principal Research Engineer (Post-Training)

Builds

Production-ready alignment algorithms, training objectives, and scalable data pipelines for large language models.

Domain

Generative AI, Large Language Models (LLMs), Reinforcement Learning, Alignment

Deliverable

production ML models

Required skills

Leading technical projects and teams, deep understanding of transformers and alignment methods, delivering applied ML systems in production, designing production-quality ML infrastructure, training and optimizing large-scale models on GPU, leading LLM training initiatives, product experimentation and A/B testing, software engineering for scalable code

Preferred skills

Hands-on experience with open-source models (Mistral, Qwen), cloud-native ML infrastructure (Kubernetes, Docker), publications in top ML conferences

Technologies

Transformers, Reinforcement Learning, Supervised Fine-Tuning, Preference Optimization, Kubernetes, Docker, GPU-based systems

Responsibilities

Define and drive the technical roadmap for mid- and post-training systems, mentor researchers and engineers, lead development of alignment algorithms and optimization techniques, design efficient training and inference systems, architect scalable data pipelines, establish best practices for experimentation and deployment

Seniority

Principal, strategy & mentorship

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