Devvm.dev: One VM for every project

devvm is a free, open-source tool for creating a separate virtual machine for each development project on macOS or Linux. It detects toolchains from project files, can install coding agents such as Claude Code, Codex, and opencode, and provides a ready-to-use shell with a single command. The project folder is mounted read-write at its usual path, while other home-directory files - such as SSH keys, cloud credentials, and documents - are kept out. Agents receive selected settings and skills, but not their history; login secrets remain on the host, with a local proxy adding real tokens to outgoing requests. New VMs use a restricted network allowlist by default, which users can tighten or loosen.

The main argument is that sandboxing code and agents can contain prompt injections, compromised dependencies, leaked secrets, or rogue behavior without requiring developers to configure a VM from scratch. devvm also forwards project ports to the host, supports opening VMs in VS Code over SSH, and carries the developer’s Git identity into commits. Shared images and read-only toolchains make subsequent VMs quick to start. Developers can customize reusable image layers, start from container images, use devcontainer.json settings, or work on a repository clone to protect their working tree. The documentation also emphasizes that isolation is not absolute: it describes remaining attack paths, and Git protection for hooks and configuration is available on macOS but not Linux.