Ktlint Formatter for VS Code

A zero-configuration VS Code extension that formats Kotlin code using ktlint. No setup required - just install and start formatting!

Features

• Zero Configuration: No ktlint installation or setup needed
• Automatic Setup: Downloads ktlint (v1.8.0) automatically on first use
• Native Integration: Works with VS Code's built-in formatting commands
• Kotlin Standard: Follows the official Kotlin coding conventions
• Script Support: Formats both .kt and .kts files
• Status Notifications: Visual feedback on formatting success/failure

Installation

From VS Code Marketplace

1. Open VS Code
2. Go to Extensions (Ctrl+Shift+X or Cmd+Shift+X on Mac)
3. Search for "Ktlint Formatter"
4. Click "Install"

Or install directly from the VS Code Marketplace

Command Line:

code --install-extension rnoro.vscode-ktlint-formatter

Usage

Manual Formatting

Open any Kotlin file (.kt or .kts) and format using:

• Keyboard: Shift + Alt + F (Windows/Linux) or Shift + Option + F (Mac)
• Context Menu: Right-click → "Format Document"
• Command Palette: Ctrl+Shift+P → "Format Document"

Auto Format on Save

Add to your VS Code settings.json:

{
  "editor.formatOnSave": true,
  "[kotlin]": {
    "editor.defaultFormatter": "rnoro.vscode-ktlint-formatter"
  },
  "[kotlin-script]": {
    "editor.defaultFormatter": "rnoro.vscode-ktlint-formatter"
  }
}

Requirements

• VS Code: 1.85.0 or later
• Java Runtime: Required to execute ktlint (check with java -version)

How It Works

1. Extension activates when you open a Kotlin file
2. On first use, ktlint binary (v1.8.0) is downloaded automatically
3. Formatting requests are processed through ktlint
4. Results are applied to your editor with status notifications

Troubleshooting

Formatting doesn't work

1. Check Output Panel: View → Output → Select "Ktlint Formatter"
2. Verify Java: Run java -version in terminal
3. Reload Extension: Press F1 → "Reload Window"

Download fails

• Check your internet connection
• Verify proxy settings if behind corporate firewall
• Check VS Code's network settings

Manual ktlint download location

Ktlint is stored at: ~/.vscode/globalStorage/rnoro.vscode-ktlint-formatter/ktlint

Contributing

Found a bug or have a feature request? Please open an issue on GitHub.

Recommended Extensions

For the best Kotlin development experience in VS Code, use this extension together with:

• Kotlin Language Server - Official Kotlin language server from JetBrains
  • Provides IntelliSense, code navigation, and refactoring
  • Developed and maintained by JetBrains

License

MIT License - see LICENSE for details

Related Resources

• ktlint Official Site
• Kotlin Coding Conventions