HOL Guard: Open-source antivirus for AI agents

HOL Guard is a free, open-source tool that sits between an AI assistant and the computer it runs on. When the assistant tries something risky, the tool pauses it and asks you first. It installs in about a minute, runs on your own machine, and a typical check takes under 50 milliseconds. Your files are never uploaded, and the whole thing works with no internet connection.

The people exposed here are anyone using Claude Code, Cursor, Codex, Gemini CLI, OpenCode, Hermes, or OpenClaw.

Balanced is the default, and it decides what you never see

HOL Guard ships four settings: Gentle, Balanced, Strict, and Paranoid. Michael Kantor, president of HOL, describes the design goal as “protect me without making the agent unusable.” In practice, he says, Balanced “asks again on things like secret/exfiltration access, destructive or encoded execution, prompt injection, dangerous MCP calls, malicious skills and persistence; warns on network egress/package scripts; and blocks attempts to bypass HOL Guard itself.”

Strict adds low-confidence signals on top of that, and Paranoid interrupts on any unfamiliar action from an external tool server. Both mean more interruptions. Neither is on by default.

The list of things that trigger a block is public on purpose