Installation

Pencil is available as an IDE extension and a standalone desktop application. Choose the option that best fits your workflow.

VS Code Extension

  1. Open VS Code.
  2. Go to the Extensions panel (Cmd/Ctrl+Shift+X).
  3. Search for "Pencil".
  4. Click Install.

Verification

Create a new file with a .pen extension. You should see the Pencil icon appear in the top-right corner of the editor.

Troubleshooting — if the icon does not appear:

  • Make sure the extension is enabled (check the Extensions sidebar for a "Disable" button next to Pencil).
  • Reload the window: Cmd/Ctrl+Shift+P → Developer: Reload Window.
  • Verify the file extension is exactly .pen (not .pen.txt).

Cursor Extension

  1. Open Cursor.
  2. Go to the Extensions panel (Cmd/Ctrl+Shift+X).
  3. Search for "Pencil".
  4. Click Install.

Common Issues

  • Extension doesn’t connect — Make sure you are logged in to Claude Code. Pencil requires an active Claude Code session to communicate with the AI backend.
  • Don’t see the prompt editor — Open a .pen file first. The prompt editor only activates when a Pencil file is in focus.
  • "You need Cursor Pro" message — Some Pencil features rely on Cursor’s built-in AI capabilities. If you see this message, verify that your Cursor plan includes Pro-level access, or use the standalone desktop app instead.

Desktop Application

macOS

Download the latest .dmg file from the Pencil website. Open the disk image and drag Pencil.app into your Applications folder.

Linux

Install with dpkg:

sudo dpkg -i pencil_latest_amd64.deb
sudo apt-get install -f   # resolve dependencies if needed

Or use the AppImage:

chmod +x Pencil-latest.AppImage
./Pencil-latest.AppImage

Windows

Download the Windows installer from the Pencil website. Run the .exe file and follow the on-screen instructions to complete the installation.

Claude Code CLI

The Claude Code CLI powers the AI features in Pencil. Install it globally via npm:

npm install -g @anthropic-ai/claude-code-cli

# Authenticate via your browser
claude

# Verify the installation
claude --version

After running claude, a browser window will open for authentication. Follow the prompts to log in and authorise the CLI.

MCP Server

The MCP server runs automatically whenever you use Pencil — no manual configuration is required.

To verify the server is running in Cursor, navigate to Settings → Tools & MCP. You should see the Pencil MCP server listed and active.

Post-Installation

  1. Complete activation — Enter your email address when prompted to activate your Pencil licence.
  2. Login to Claude Code — Run claude in your terminal and authenticate via the browser to enable AI-powered features.
  3. Open the welcome file — Pencil creates a welcome.pen file automatically. Open it to explore the interface.
  4. Create your first design — Start a new .pen file and begin sketching. Pencil will guide you through the basics.

Updating

Extensions (VS Code and Cursor) update automatically when a new version is published to the marketplace. No action is required on your part.

Desktop application — You will receive an in-app notification when a new version is available. Follow the prompt to download and install the update.

Last updated: February 22, 2026