Numbat is an open-source security enforcement harness and policy engine developed by Perplexity AI. Written in Go, it is engineered to inspect, intercept, and govern actions executed by AI coding agents and development environments. In day-to-day operation, Numbat functions as an execution guardrail that evaluates agent tool calls and commands against deterministic security policies. It evaluates rules using embedded Common Expression Language (CEL) expressions to validate shell executions, PowerShell commands, and file operations before they are executed in the development environment. What distinguishes Numbat from conventional agent orchestrators is its strict focus on security policy enforcement and tamper prevention. Rather than focusing on prompt routing or agent autonomy, it provides runtime enforcement hooks (including integrations for editors like Cursor) to prevent autonomous agents from modifying critical agent configurations or running unauthorized scripts. Numbat is open-source software maintained by Perplexity AI under a standard GitHub open-source repository structure. It operates locally as a compiled Go binary or runtime hook without mandatory cloud platform subscriptions.
Tags: AI, ai agent, cli, developer tools, OpenSource