# Principal Research Engineer, Post-Training

Hiring organization: [CharacterAI](https://career.thegoodapps.co/organizations/characterai)

Canonical page: https://career.thegoodapps.co/jobs/db6a734b-ff12-4251-a680-db6f36e9eb0d

Listed on CharacterAI's own careers site. Applications go to them directly.

- Seniority: Principal
- Location: Redwood City, CA
- Salary: 275000 – 400000 USD per year

## Summary

Lead the technical vision and execution of post-training systems for large language models at Character.AI, where you'll architect the algorithms and infrastructure that power conversational AI experiences for millions of users. This role combines deep ML expertise with team leadership, requiring you to drive advances in alignment, optimization, and model evaluation while mentoring researchers and engineers across a cross-functional organization.

_Our summary, not CharacterAI's wording._

## Skills named

Docker, Kubernetes, Python, Reinforcement Learning

## Required

- PhD in Computer Science, Machine Learning, AI, or equivalent industry experience
- Leadership experience with technical projects or research teams
- Deep understanding of modern ML techniques including transformers and LLMs
- Track record of delivering impactful research or production ML systems
- Expertise in production-quality ML systems and infrastructure
- Experience training and optimizing large-scale models on GPU systems
- Experience leading teams on LLM training, mid-training, or post-training
- Experience with product experimentation and A/B testing frameworks
- Strong software engineering skills
- Excellent communication and cross-functional leadership skills

## Nice to have

- Hands-on experience with Mistral, Qwen, or similar open-source models for role-playing applications
- Familiarity with cloud-native ML infrastructure like Kubernetes and Docker
- Publications at leading ML conferences or AI community contributions

Apply on CharacterAI's site: https://jobs.ashbyhq.com/character/cab23a8b-97ba-4b20-a8e3-f7d9a61e13f4/application