Character.AI
AI & Machine LearningDirect Ashby career site

Research Engineer, Post-Training (All Industry Levels)

Location
Remote (US) · On-site
Job type
Full-time
Level
Mid-level
Education
Doctorate
Listed
23 days ago

Skills & highlights for this role

  • reinforcement learning
  • transformers
  • data pipelines
  • GPU training
  • distributed training

Also useful

  • Kubernetes
  • Docker
  • A/B testing

About the Role and Team

Joining us as a Research Engineer on the Post-Training team, you'll be diving into the exciting world of fine-tuning AI models, optimizing their performance, and ensuring they meet the highest standards of quality and efficiency. Your work will directly contribute to our groundbreaking advancements in AI, helping shape an era where technology is not just a tool, but a companion in our daily lives.

The Post-Training team is responsible for developing our powerful pretrained language models into intelligent, engaging, and aligned products.

As a Post-Training Researcher, you will work across teams and our technical stack to improve our model performance and training methods, including data, compute and algorithms. You will get to shape the conversational experience of millions of users per day.

What You'll Do

  • Develop alignment algorithms and loss functions to improve data sample efficiency.
  • Write data pipelines to process diverse web data into a format models can ingest.
  • Identify quality signals to understand our model’s performance in the real world.
  • Design sampling algorithms to improve serving efficiency of large generative models.

Who You Are

  • "All Industry Levels": have at least PhD (or equivalent)
  • Write clear and clean production-facing and training code
  • Experience working with GPUs (training, serving, debugging)
  • Experience with data pipelines and data infrastructure
  • Strong understanding of modern machine learning techniques (reinforcement learning, transformers, etc)
  • Track-record of exceptional research or creative applied ML projects

Nice to Have

  • Experience with product experimentation and A/B testing
  • Experience training large models in a distributed setting
  • Familiarity with ML deployment and orchestration (Kubernetes, Docker, cloud)
  • Publications in relevant academic journals or conferences in the field of machine learning

About Character.AI

Character.AI empowers people to connect, learn and tell stories through interactive entertainment. Our platform lets users engage with tens of millions of characters, enjoy unlimited conversations, and embark on infinite adventures.

In just two years, we achieved unicorn status and were honored as Google Play's AI App of the Year-a testament to our innovative technology and visionary approach.

Join us and be a part of establishing this new entertainment paradigm while shaping the future of Consumer AI!

Read the original posting

From Character.AI's careers page, first listed on Rolev.ai on October 17, 2026. Rolev.ai is not the employer.

How Rolev.ai helps with this application

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Common questions

Where is the Research Engineer, Post-Training (All Industry Levels) job at Character.AI located?

Yes, this Research Engineer, Post-Training (All Industry Levels) opening at Character.AI is listed as Remote (US) (On-site). Always check Character.AI's application page for specific state eligibility or relocation policies.

What qualifications are required for Research Engineer, Post-Training (All Industry Levels) at Character.AI?

For the Research Engineer, Post-Training (All Industry Levels) role, Character.AI highlights a doctorate; experience with reinforcement learning, transformers, data pipelines, GPU training, distributed training. Rolev.ai can score your existing resume against these requirements and show any skill gaps before you apply.

How do I apply for the Research Engineer, Post-Training (All Industry Levels) position at Character.AI?

This listing links directly to Character.AI's Ashby application page. You can apply directly on Character.AI's site, or use Rolev.ai to check your resume fit, generate a zero-hallucination tailored resume and cover letter for this posting, and autofill the Ashby application form in 1 click with the Rolev.ai Chrome extension. You always review the form and press Submit yourself.