Matchlock introduces a Linux-based sandboxing solution designed specifically to secure AI agent workloads. This CLI tool creates ephemeral microVMs to isolate AI agents, preventing sensitive data like API keys from ever entering the guest environment. By default, everything is blocked, with network access only allowed via explicit allowlists and secrets injected through a transparent proxy.

The sandbox boots in under a second, providing a disposable, locked-down Linux environment that doesn't impact the host machine. AI agents gain full Linux capabilities - installing packages, writing files - while the host remains untouched. Each sandbox uses a copy-on-write filesystem that vanishes upon completion. Matchlock supports both Linux and macOS (Apple Silicon), offering similar CLI behavior across platforms. Its core innovation lies in the MITM proxy mechanism, where real credentials are injected in-flight, leaving placeholders in the VM. This approach eliminates the risk of credential leaks even if an agent is compromised.

The project includes Go and Python SDKs for embedding sandboxes directly into applications, allowing programmatic VM launch, command execution, and file operations. The architecture leverages Firecracker or Virtualization.framework for lightweight virtualization, with Linux using nftables DNAT and macOS employing built-in NAT. Matchlock is open-source under the MIT license, with a GitHub repository showing 21 stars as of February 2026. This tool addresses a critical security gap in running AI agents by providing robust isolation without sacrificing functionality.