Senior Security Engineer, AI Security

Reddit is a community of communities. It’s built on shared interests, passion, and trust, and is home to the most open and authentic conversations on the internet. Every day, Reddit users submit, vote, and comment on the topics they care most about. With 100,000+ active communities and approximately 130 million daily active unique visitors, Reddit is one of the internet’s largest sources of information. For more information, visit www.redditinc.com.

About The Role

Reddit is a community of communities. It is built on shared interests, passion, and trust and is home to some of the most open and authentic conversations on the internet. Every day, Reddit users submit, vote, and comment on the topics they care most about.

Reddit is hiring a Senior Security Engineer, AI Security to help teams build and ship AI-powered products securely. This role combines product security judgment with hands-on engineering to secure the systems, tools, and workflows behind Reddit's AI efforts.

You will review AI-powered product designs, threat model LLM and agentic workflows, and build reusable security primitives that make secure AI development easier for teams across Reddit. This is not an MLE role, but you should be comfortable reasoning about how AI systems fail, how agents use tools, and how security controls fit into inference, retrieval, tool-use, and execution paths.

The best candidates combine practical application security judgment with strong builder instincts. They can identify risks before launch, then turn repeated findings into guardrails, scanners, registries, sandboxes, libraries, policy checks, or platform controls that scale beyond one product team.

What You'll Do

• Review and threat model AI-powered product features, LLM integrations, agentic workflows, MCP servers, tools, plugins, retrieval systems, model outputs, and internal AI tools before launch.
• Build reusable AI security primitives such as guardrails, scanners, policy checks, tool-use controls, registries, sandboxes, libraries, and workflow-native enforcement points.
• Design security tooling that can sit in the inference, retrieval, or execution path to