mise Development Environment Manager

A polyglot development environment manager pronounced meez, inspired by the French culinary concept mise en place meaning everything in its place, currently at version 2026.6.13 under the MIT license and developed by Jeff Dickey through en.dev with sponsorship from 37signals and CodeRabbit. The tool consolidates three previously separate concerns into a single command-line interface and configuration file: dev tool version management installing and automatically switching between 900-plus programming language runtimes and command-line tools including Node, Python, Ruby, Go, Rust, Java, Deno, Bun, Terraform, kubectl, Zig, Swift, PHP, and Elixir as developers move between project directories; environment variable management loading project-specific variables from mise.toml, .env files, shell commands, and external sources; and task orchestration defining build, test, lint, and deploy commands next to the tools and environment variables they depend on. A single mise.toml file replaces the combination of .tool-versions, .nvmrc, .python-version, .ruby-version, direnv .envrc, and Makefiles that teams previously maintained separately, ensuring reproducible environments across developer machines and continuous integration pipelines. The tool activates versions through shell hooks that run on directory change with near-zero overhead, and integrates with existing lockfiles and package managers rather than replacing them. Installation takes one command via curl, and a built-in doctor command validates the setup is ready. The project also develops aube, a fast Node.js package manager that uses existing lockfiles and is available in beta.