fnm — Fast and Simple Node.js Version Manager

What it is

fnm (Fast Node Manager) is a Node.js version manager built in Rust. It installs and switches between Node.js versions instantly, supports .node-version and .nvmrc files, and works on macOS, Linux, and Windows. fnm is a drop-in replacement for nvm with dramatically faster performance.

fnm is for any JavaScript or TypeScript developer who works across multiple projects requiring different Node.js versions.

The project is actively maintained with regular releases and a growing user community. Documentation covers common use cases, and the open-source nature means you can inspect the source code, contribute fixes, and adapt the tool to your specific requirements.

How it saves time or tokens

Traditional version managers like nvm add noticeable shell startup latency (200-500ms per new terminal). fnm loads in under 1ms because it is a compiled Rust binary, not a shell script. Automatic version switching via .node-version files means you never run the wrong Node version in a project directory.

How to use

1. Install fnm via curl, brew, or cargo.
2. Add the shell integration to your shell profile (bash, zsh, fish, or PowerShell).
3. Run fnm install <version> and fnm use <version> to manage Node.js versions.

Example

# Install fnm
curl -fsSL https://fnm.vercel.app/install | bash

# Or via Homebrew
brew install fnm

# Add to .zshrc
eval "$(fnm env --use-on-cd)"

# Install and use Node.js versions
fnm install 22
fnm use 22
node --version  # v22.x.x

# Auto-switch: create .node-version
echo '20' > .node-version
cd .  # fnm switches to Node 20 automatically

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Common pitfalls

• Forgetting to add eval "$(fnm env --use-on-cd)" to your shell profile means automatic version switching will not work.
• fnm and nvm can conflict if both are installed. Remove nvm initialization from your shell profile before switching to fnm.
• On Windows, fnm requires the --shell powershell flag for proper integration with PowerShell.

Before adopting this tool, evaluate whether it fits your team's existing workflow. Read the official documentation thoroughly, and start with a small proof-of-concept rather than a full migration. Community forums, GitHub issues, and Stack Overflow are valuable resources when you encounter edge cases not covered in the documentation.