aradotso/open-pencil-design-editor

OpenPencil Design Editor

Skill by ara.so — Daily 2026 Skills collection.

OpenPencil is an open-source, AI-native design editor that reads and writes native Figma (.fig) files, provides a headless CLI, an MCP server for AI agents, and a Vue SDK for building custom editors. It is MIT-licensed and runs in the browser, as a desktop app (Tauri/macOS/Windows/Linux), or fully headlessly.

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Installation

Web app (no install)

Visit app.openpencil.dev/demo.

Desktop (macOS)

brew install open-pencil/tap/open-pencil

Or download from releases.

CLI

bun add -g @open-pencil/cli

MCP server

bun add -g @open-pencil/mcp

Local development

git clone https://github.com/open-pencil/open-pencil
cd open-pencil
bun install
bun run dev          # Web app at localhost:1420
bun run tauri dev    # Desktop (requires Rust)

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CLI Reference

The open-pencil CLI operates on .fig files headlessly. When the desktop app is running, omit the file argument to connect to the live canvas via RPC.

Inspect file structure

# Print the full node tree
open-pencil tree design.fig

# Find nodes by type
open-pencil find design.fig --type TEXT
open-pencil find design.fig --type FRAME

# Get a specific node by ID
open-pencil node design.fig --id 1:23

# File metadata
open-pencil info design.fig

XPath queries

# All frames
open-pencil query design.fig "//FRAME"

# Frames narrower than 300px
open-pencil query design.fig "//FRAME[@width < 300]"

# Text nodes whose name contains "Button"
open-pencil query design.fig "//TEXT[contains(@name, 'Button')]"

# Nodes with rounded corners
open-pencil query design.fig "//*[@cornerRadius > 0]"

# Text inside sections
open-pencil query design.fig "//SECTION//TEXT"

Export

# PNG (default)
open-pencil export design.fig

# JPG at 2x scale, quality 90
open-pencil export design.fig -f jpg -s 2 -q 90

# SVG
open-pencil export design.fig -f svg

# WEBP
open-pencil export design.fig -f webp

# JSX with Tailwind v4 utility classes
open-pencil export design.fig -f jsx --style tailwind

Example Tailwind output:

<div className="flex flex-col gap-4 p-6 bg-white rounded-xl">
  <p className="text-2xl font-bold text-[#1D1B20]">Card Title</p>
  <p className="text-sm text-[#49454F]">Description text</p>
</div>

Design token analysis

open-pencil analyze colors design.fig
open-pencil analyze typography design.fig
open-pencil analyze spacing design.fig
open-pencil analyze clusters design.fig   # Repeated structures / component candidates

Scripting with Figma Plugin API (eval)

# Read: count children on the current page
open-pencil eval design.fig -c "figma.currentPage.children.length"

# Read: get all text node contents
open-pencil eval design.fig -c "figma.currentPage.findAll(n => n.type === 'TEXT').map(n => n.characters)"

# Write: set opacity of all selected nodes (-w writes back to file)
open-pencil eval design.fig -c "figma.currentPage.selection.forEach(n => n.opacity = 0.5)" -w

# Write: rename all frames on the page
open-pencil eval design.fig -c "figma.currentPage.findAll(n => n.type === 'FRAME').forEach((f, i) => f.name = 'Frame ' + i)" -w

# Connect to the live running desktop app (no file arg)
open-pencil eval -c "figma.currentPage.name"
open-pencil tree
open-pencil export -f png

All commands support --json for machine-readable output:

open-pencil find design.fig --type TEXT --json
open-pencil analyze colors design.fig --json

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MCP Server

The MCP server exposes 90 tools (87 core + 3 file management) for AI agents to read and write .fig files.

Stdio (Claude Code, Cursor, Windsurf)

bun add -g @open-pencil/mcp

Add to your MCP client config (e.g. ~/.claude/mcp.json or Cursor settings):

{
  "mcpServers": {
    "open-pencil": {
      "command": "openpencil-mcp"
    }
  }
}

HTTP server (scripts, CI)

openpencil-mcp-http
# Listens at http://localhost:3100/mcp

Claude Code desktop integration

1. Install the ACP adapter:

   npm i -g @zed-industries/claude-agent-acp
   

2. Add MCP permission to ~/.claude/settings.json:

   {
     "permissions": {
       "allow": ["mcp__open-pencil"]
     }
   }
   

3. Open the desktop app → Ctrl+J → select Claude Code from the provider dropdown.

Agent skill (quick setup)

npx skills add open-pencil/skills@open-pencil

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AI Chat (Built-in)

• Open with ⌘J (macOS) or Ctrl+J (desktop/web).
• 87 tools: create shapes, set fills/strokes, manage auto-layout, work with components and variables, boolean operations, token analysis, asset export.
• Bring your own API key — no backend or account required.

Supported providers

Configure via the provider dropdown in the chat panel:

| Provider | Env var | |---|---| | Anthropic | ANTHROPIC_API_KEY | | OpenAI | OPENAI_API_KEY | | Google AI | GOOGLE_AI_API_KEY | | OpenRouter | OPENROUTER_API_KEY | | Any compatible endpoint | Custom base URL |

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Real-time Collaboration

No server, no account. Peer-to-peer via WebRTC.

1. Click the Share button (top-right).
2. Share the generated URL: app.openpencil.dev/share/<room-id>.
3. Peers see live cursors, selections, and edits.
4. Click a peer's avatar to follow their viewport.

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Project Structure

packages/
  core/     @open-pencil/core  — engine: scene graph, renderer, layout, codec
  cli/      @open-pencil/cli   — headless CLI
  mcp/      @open-pencil/mcp   — MCP server (stdio + HTTP)
  docs/     Documentation site
src/        Vue 3 app — components, composables, stores
desktop/    Tauri v2 (Rust + config)
tests/      E2E (188 tests) + unit (764 tests)

Tech stack

| Layer | Technology | |---|---| | Rendering | Skia (CanvasKit WASM) | | Layout | Yoga WASM (flex + CSS Grid) | | UI | Vue 3, Reka UI, Tailwind CSS 4 | | File format | Kiwi binary + Zstd + ZIP | | Collaboration | Trystero (WebRTC P2P) + Yjs (CRDT) | | Desktop | Tauri v2 | | AI/MCP | Anthropic, OpenAI, Google AI, OpenRouter; MCP SDK; Hono |

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Development Commands

bun run dev        # Start web dev server (localhost:1420)
bun run tauri dev  # Start desktop app (requires Rust)
bun run check      # Lint + typecheck
bun run test       # E2E visual regression tests
bun run test:unit  # Unit tests
bun run format     # Code formatting
bun run tauri build  # Production desktop build

Desktop prerequisites: Rust + Tauri v2 platform deps.

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Common Patterns

Batch-rename all text nodes in a .fig file

open-pencil eval design.fig \
  -c "figma.currentPage.findAll(n => n.type === 'TEXT').forEach((t, i) => t.name = 'Text_' + i)" \
  -w

Extract all colors as JSON

open-pencil analyze colors design.fig --json > colors.json

Export every frame as PNG in CI

for id in $(open-pencil find design.fig --type FRAME --json | jq -r '.[].id'); do
  open-pencil export design.fig --id "$id" -f png -o "frames/$id.png"
done

Query nodes matching a naming convention

# Find all nodes named with a "btn-" prefix
open-pencil query design.fig "//*[starts-with(@name, 'btn-')]"

Connect an MCP client to a running desktop app

When the desktop app is open, the MCP stdio server can connect to the live canvas. No file path needed — all reads and writes go to the open document.

{
  "mcpServers": {
    "open-pencil": {
      "command": "openpencil-mcp"
    }
  }
}

Export a selection as Tailwind JSX programmatically

open-pencil export design.fig --id 1:23 -f jsx --style tailwind

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Troubleshooting

openpencil-mcp not found after install

• Ensure bun's global bin dir is on your PATH: export PATH="$HOME/.bun/bin:$PATH"
• Or use npx openpencil-mcp as the MCP command value.

Desktop app CLI connection fails

• The desktop app must be running before issuing commands without a file argument.
• Check that no firewall rule blocks the local RPC socket.

Tauri dev build errors

• Install platform prerequisites: v2.tauri.app/start/prerequisites
• Ensure Rust is up to date: rustup update

.fig file won't open

• Confirm the file was exported from Figma (not a .fig backup or plugin artifact).
• Run open-pencil info design.fig to check if the codec can parse the header.

AI chat returns no response

• Verify your API key is set correctly in the provider settings panel.
• For OpenRouter, ensure your key has credits and the selected model is available.

Collaboration peers not connecting

• Both peers must use the exact same share URL (room ID is case-sensitive).
• WebRTC requires both peers to allow the browser/app through any firewall.

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Links

• Web app: app.openpencil.dev/demo
• Documentation: openpencil.dev
• MCP tools reference: openpencil.dev/reference/mcp-tools
• Releases: github.com/open-pencil/open-pencil/releases
• License: MIT