Kopi - JDK Version Manager

Kopi is a JDK version management tool written in Rust that integrates with your shell to seamlessly switch between different Java Development Kit versions.

Full documentation at https://kopi-vm.github.io/

Installation

Homebrew (macOS)

brew install kopi-vm/tap/kopi

PPA (Ubuntu/Debian)

# Import GPG key
curl -fsSL https://keyserver.ubuntu.com/pks/lookup?op=get\&search=0xD2AC04A5A34E9BE3A8B32784F507C6D3DB058848 | \
  gpg --dearmor | \
  sudo tee /usr/share/keyrings/kopi-archive-keyring.gpg > /dev/null

# Add repository
echo "deb [arch=amd64,arm64 signed-by=/usr/share/keyrings/kopi-archive-keyring.gpg] \
  https://kopi-vm.github.io/ppa-kopi $(lsb_release -cs) main" | \
  sudo tee /etc/apt/sources.list.d/kopi.list > /dev/null

# Install
sudo apt update && sudo apt install kopi

Windows Package Manager

winget install kopi

Scoop (Windows)

scoop bucket add kopi https://github.com/kopi-vm/scoop-kopi
scoop install kopi

Cargo (All platforms)

cargo install kopi

Post-installation Setup

# Initial setup
kopi setup

# Add to PATH (in ~/.bashrc, ~/.zshrc, or ~/.config/fish/config.fish)
export PATH="$HOME/.kopi/shims:$PATH"

Quick Start

Essential Commands

# Install JDKs
kopi install 21                    # Latest JDK 21 (Eclipse Temurin by default)
kopi install temurin@17           # Specific distribution and version
kopi install corretto@11.0.21     # Exact version

# List installed JDKs
kopi list

# Set versions
kopi global 21                    # Set global default
kopi local 17                     # Set project version (creates .kopi-version)
kopi shell 11                     # Temporary shell override

# Show current JDK
kopi current
kopi which java                   # Path to java executable

# Search available JDKs
kopi search 21                    # Search for JDK 21 variants
kopi search corretto              # List all Corretto versions

# Uninstall JDKs
kopi uninstall temurin@21

Working with Projects

# Create version file for project
cd my-project
kopi local 17                     # Creates .kopi-version

# Kopi automatically switches when entering directories with version files
cd my-java-21-project            # Automatically switches to Java 21
cd my-java-17-project            # Automatically switches to Java 17

Development

Prerequisites

• Rust toolchain (1.70+)
• sccache (recommended): cargo install sccache

Building from Source

git clone https://github.com/kopi-vm/kopi.git
cd kopi

# Development build
cargo build

# Run tests
cargo test

# Release build
cargo build --release

Development Workflow

When completing any coding task:

1. Run cargo fmt to format code
2. Run cargo clippy --all-targets -- -D warnings to check for improvements
3. Run cargo test --lib --quiet to run unit tests
4. Submit a pull request

All commands must pass without errors before considering work complete.

Contributing

We welcome contributions! Please see our Contributing Guidelines for details.

Documentation

• User Documentation: https://kopi-vm.github.io/
• Architecture Decision Records: docs/adr/
• Developer Reference: CLAUDE.md

License

Kopi is licensed under the Apache License 2.0. See LICENSE for details.

Acknowledgments

• JDK metadata originally sourced from foojay.io and optimized for fast access
• Inspired by volta, nvm, and pyenv

Built with ❤️ by the Kopi team