devvm

devvm is an open-source command-line tool from devvmhq that gives each project folder its own isolated virtual machine, equipped with the toolchain the project calls for. It is meant for developers and for coding agents such as Claude Code, Codex and opencode, which run inside the VM instead of on the host. The project is MIT-licensed, and the latest release listed is v0.1.0.

What It Is

devvm is a sandbox manager for development work. Running devvm in a project folder shows what the new VM will get, including toolchains, agent, size and network tier, and asks whether to customize it. Confirming opens a shell in the VM at the same path as on the host, with a (devvm) prompt, and running devvm again in the folder reopens the same VM.

How the isolation works

The VM mounts only the project folder, so locations such as ~/.ssh, ~/.aws and ~/Documents stay out of reach. New VMs use the allowlist network tier, where traffic goes through a proxy on the host and only allowlisted hosts are reachable. Looser tiers (internet, open) and a stricter one (none) are available. Secrets such as the Claude Code token stay on the host: the VM holds placeholders and the proxy inserts the real values. On macOS, devvm locks .git hooks and config. With --clone, the VM works on its own clone of the repo and its work reaches the host repo only when fetched. The docs state that no sandbox closes every gap and list the remaining attack vectors.

Toolchains, agents and layers

devvm detects toolchains from project files, for example package.json yields node. Claude Code, Codex and opencode can run in the VM with the user's settings, skills and MCP servers, and devvm agent import copies them in from existing agents. Built-in layers are docker, nix and desktop, and devvm layer new creates custom layers. A VM can start from a container image with --from, or be configured from a project's devcontainer.json. Ports forward automatically, and devvm code opens the VM in VS Code over Remote-SSH.

Setup path

devvm runs on macOS 13 or newer and on Linux, on arm64 or x86_64, using Lima as its backend (Apple's Virtualization framework on macOS, QEMU on Linux). Install it with Homebrew or an install script, then run devvm doctor to check requirements. The first run builds a base image once, and later VMs are copies that start in seconds.