GitHub - smol-machines/smolvm: Tool to build & run portable, lightweight, self-contained virtual machines.

smolvm is an open-source CLI tool for building and running portable, lightweight virtual machines with sub-second cold starts on macOS and Linux. Each workload gets real hardware isolation via its own kernel using Hypervisor.framework (macOS) or KVM (Linux), powered by libkrun. Key features include: sandboxing untrusted code with network egress controls, packing stateful VMs into a single portable .smolmachine file, persistent development environments, SSH agent forwarding without exposing private keys, and declarative Smolfile configuration. Memory is elastic via virtio balloon, and the tool compares favorably to containers, QEMU, Firecracker, and Kata in terms of portability and macOS native support.