Senior Machine Learning Engineer, GenAI Security

About Reddit

Reddit is a community of communities built on shared interests, passion, and trust. With 100,000+ active communities and approximately 126 million daily active unique visitors, Reddit is one of the internet's largest sources of information.

About the GenAI Security Team

The GenAI Security team protects Reddit's GenAI usage across employee tools, internal agents, and production user-facing systems. The mission is to secure and protect Reddit's AI traffic and GenAI adoption by default.

Role Overview

Building zero-trust, defense-in-depth systems that verify identity, permissions, data access, and semantic intent across AI workflows. A core part of this work is developing practical, high-quality ML models that detect and prevent security risks.

Key Responsibilities

• Lead model development for GenAI Security
• Establish strong ML practices across the security organization
• Own the full machine learning lifecycle: problem definition, data ETL, feature engineering, model training, model evaluation, deployment, experimentation, and prediction monitoring
• Detect and prevent security risks such as prompt injection, jailbreak attempts, sensitive data exfiltration, unsafe model behavior, anomalous usage, and unauthorized agent actions