# Principal Research Engineer, Post-Training at Character.AI

- Company: Character.AI
- What the company does: Backed by Lightspeed and a16z.
- Company website: https://character.ai/
- Type: Startups (AI role)
- Level: Principal and up
- Location: Redwood City, CA
- Work setup: On-site
- Pay: $275K to $400K base salary per year (USD)
- Posted: 2026-06-22
- Apply by: 2026-10-08
- Apply: https://jobs.ashbyhq.com/character/cab23a8b-97ba-4b20-a8e3-f7d9a61e13f4
- Page: https://www.1752.vc/careers/jobs/character-ai-principal-research-engineer-post-training/

## About the role

Technical Leadership & Mentorship: Define and drive the technical roadmap for mid- and post-training systems, balancing research innovation with production reliability and scalability. You will mentor and grow a team of researchers and engineers through technical guidance, design reviews, and career development. Establish best practices for experimentation, model development, and deployment.

## What they're looking for

- PhD in Computer Science, Machine Learning, AI, or a related field, or equivalent industry experience
- Significant experience leading technical projects or teams in machine learning, AI research, or large-scale distributed systems. Experience scaling and mentoring high-performing research and engineering teams
- Deep understanding of modern machine learning techniques, including transformers, reinforcement learning, alignment methods, and large language models
- Strong track record of delivering impactful research or applied ML systems in production environments
- Expertise in designing, building, and maintaining production-quality ML systems and infrastructure
- Experience training, serving, debugging, and optimizing large-scale models on GPU-based systems

Tags: Technical Staff - ML