Research Engineer, AI Safety & Alignment

Location: Hybrid in Redwood City, California, United States

Compensation: $225K–$400K plus equity

Company

Character.AI develops interactive AI entertainment products that help people connect, learn, and tell stories, serving more than 20 million visitors.

What you will do

• Develop evaluation methodologies and metrics for the safety and alignment of large language models.
• Research alignment, value learning, interpretability, and other techniques for making models robust, honest, and harmless.
• Conduct adversarial testing to identify vulnerabilities and failure modes.
• Analyze and mitigate bias, toxicity, and harmful model behavior using methods such as RLHF and fine-tuning.
• Translate safety research into practical, scalable solutions with engineering and product teams.
• Contribute to the AI safety research community through publications and presentations.

Requirements

• PhD or equivalent experience in computer science, machine learning, or a related field.
• Strong understanding of modern machine learning, especially transformers and reinforcement learning, with attention to safety implications.
• Ability to write clear production-facing and training code.
• Experience working with GPUs for training, serving, and debugging, plus data pipelines and data infrastructure.
• Passion for responsible AI development and solving complex safety challenges.

Nice to have

• Experience with product experimentation, A/B testing, and distributed large-model training.
• Familiarity with ML deployment and orchestration using Kubernetes, Docker, and cloud platforms.
• Experience with explainable AI, interpretability, AI safety, alignment, ethics, policy, or governance.
• Publications in relevant machine learning journals or conferences.

Culture & Benefits

• Health coverage for employees and families, with most premiums covered.
• Generous 401(k) contribution.
• Up to 20 weeks of paid parental leave.
• Four weeks of paid time off.
• Daily in-office catering, monthly DoorDash stipend, and monthly wellness stipend.
• Commitment to diversity and equal opportunity.