fnm vs RVM

fnm is a free Node.js version manager built in Rust for developers working from a command line or shell. It runs on macOS, Windows, and Linux, and is distributed as a single file through installation scripts, package managers, Cargo, or release binaries. It reads `.node-version` and `.nvmrc` files, so projects can specify a Node.js version. Shell setup can also enable automatic version switching when changing directories. The project provides setup instructions for Bash, Zsh, Fish, PowerShell, Windows Command Prompt, and Cmder. Its binary includes completions for Bash, Zsh, Fish, and PowerShell. On macOS and Linux, the installation script requires `curl` and `unzip`. The repository identifies the license as GPL-3.0 and invites pull requests, with issues available for project interaction. No paid plans are listed. The project page reports no published security advisories, while also noting that it has not set up a SECURITY.md file.

RVM is a command-line tool for installing and managing Ruby versions and gem sets. It can create a self-contained environment for each project, with a selected Ruby version and the gems that project needs. Named gemsets organize gems across Ruby versions, and a shared cache stores one on-disk copy of each downloaded gem. RVM can run test suites, rake tasks, benchmarks, and gem commands against multiple Ruby versions at the same time, supporting consistent setups across development, CI, QA, staging, and production. Its commands cover installing, selecting, upgrading, reinstalling, uninstalling, and removing Ruby versions. Documented integrations include Bundler, Capistrano, Chef, Jenkins, Heroku, and Passenger. RVM supports most UNIX-like systems and Windows through Cygwin or Bash on Ubuntu on Windows. Basic installation needs Bash, curl, gpg2, and GNU tools; git is needed for head Ruby versions. It documents single-user, multi-user, and mixed-mode installs, and recommends single-user mode for an isolated home-directory setup. RVM is free and maintained by community volunteers.