OpenPencil

Open-source vector design tool with a Design-as-Code philosophy. An alternative to Pencil.dev.

Design visually on an infinite canvas, generate code from designs, and let AI build entire screens from a single prompt — all in one tool that runs in your browser or as a native desktop app.

Highlights

• Infinite canvas — pan, zoom, smart alignment guides, drag-and-drop into auto-layout frames
• Drawing tools — Rectangle, Ellipse, Line, Pen (Bezier), Frame, Text, Icon picker, Image import
• Auto-layout — Vertical / horizontal layout with gap, padding, justify, align — like CSS Flexbox
• Design variables — Color / number / string tokens with multi-theme support and CSS sync
• Code generation — Export to React + Tailwind, HTML + CSS, or CSS Variables
• AI assistant — Generate full-page designs from text prompts with streaming canvas insertion
• Desktop app — Native macOS, Windows, and Linux builds via Electron
• .pen files — JSON-based, human-readable, Git-friendly

Quick Start

Prerequisites

• Bun >= 1.0
• Node.js >= 18 (for npx tooling)

Web (Development)

bun install
bun --bun run dev

Open http://localhost:3000 and click New Design to enter the editor.

Desktop (Electron)

# Development: Vite dev server + Electron
bun run electron:dev

# Production build (current platform)
bun run electron:build

AI Configuration

The AI assistant supports multiple providers:

Provider	Setup
Anthropic API	Set ANTHROPIC_API_KEY in .env
Claude Code	No config — uses Claude Agent SDK with local OAuth
OpenCode	Connect via OpenCode SDK in Agent Settings (Cmd+,)

Features

Canvas

• Infinite canvas with pan (Space+drag / middle mouse) and zoom (scroll wheel)
• Smart alignment guides with edge, center, and distance snapping
• Dimension labels during manipulation
• Frame labels and boundaries
• Double-click to enter frames (Figma-style)
• Drag-and-drop into auto-layout frames with insertion indicators

Drawing Tools

• Shapes — Rectangle, Ellipse, Line, Polygon
• Frame — Container with optional auto-layout (vertical / horizontal)
• Text — Click-to-place with full typography controls
• Pen tool — Bezier curve drawing with anchor points, control handles, path closure
• Icon picker — Search and import icons via Iconify API
• Image import — PNG, JPEG, SVG, WebP, GIF (SVG parsed into editable PenNodes)

Property Editing

• Position, size, rotation
• Fill: solid color and gradients (linear, radial)
• Stroke: color, width, dash patterns
• Corner radius (unified or per-corner)
• Opacity, visibility, lock, flip
• Effects: shadow and blur
• Auto-layout: direction, gap, padding, justify-content, align-items
• Variable binding via variable picker

Design Variables & Tokens

• Variables panel (Cmd+Shift+V): floating, resizable
• Types: Color (picker + hex + opacity), Number, String
• Multi-theme: multiple theme axes, each with variants (e.g. Light / Dark)
• $variable references: bind fill, stroke, opacity, gap, padding to tokens
• CSS sync: auto-generated CSS custom properties with per-theme variant blocks
• Code output: var(--name) for variable-bound properties

Layer Panel

• Hierarchical tree view with expand/collapse
• Drag-and-drop reordering (above / below / inside zones)
• Visibility and lock toggles, rename, context menu
• Selection synced with canvas

Code Generation

• React + Tailwind CSS
• HTML + CSS
• CSS Variables from design tokens
• Code panel: Cmd+Shift+C

AI Assistant

• Chat panel (Cmd+J) with streaming responses
• Orchestrator-based parallel generation: decomposes pages into spatial sub-tasks
• Real-time JSONL streaming with staggered fade-in animation on canvas
• Design modification mode: select elements, then describe changes
• Multi-provider: Anthropic API, Claude Code, OpenCode

History & Clipboard

• Undo / Redo with batched operations (Cmd+Z / Cmd+Shift+Z, up to 300 states)
• Copy, Cut, Paste, Duplicate (Cmd+C/X/V/D)
• Group / Ungroup (Cmd+G / Cmd+Shift+G)

File Operations

• Save / open .pen files (JSON-based, Git-friendly)
• Auto-save with File System Access API
• Per-layer export: PNG / SVG at 1x / 2x / 3x (Cmd+Shift+E)

Keyboard Shortcuts

Shortcut	Action
V	Select tool
R	Rectangle
O	Ellipse
L	Line
T	Text
F	Frame
P	Path (pen tool)
H	Hand (pan)
Cmd+A	Select all
Cmd+Z / Cmd+Shift+Z	Undo / Redo
Cmd+C / X / V / D	Copy / Cut / Paste / Duplicate
Cmd+G / Cmd+Shift+G	Group / Ungroup
Cmd+S	Save
Cmd+Shift+E	Export
Cmd+Shift+C	Code panel
Cmd+Shift+V	Variables panel
Cmd+J	AI chat
Cmd+,	Agent settings
Delete / Backspace	Delete selected
Arrow keys	Nudge 1px (+Shift = 10px)
[ / ]	Reorder layers
Escape	Deselect / Cancel

Tech Stack

Layer	Technology
Framework	TanStack Start (React 19, SSR, file-based routing)
Canvas	Fabric.js v7
State	Zustand v5
UI	shadcn/ui (Radix + Tailwind)
Styling	Tailwind CSS v4
Icons	Lucide React
Server	Nitro
Desktop	Electron 35 + electron-builder
AI	Anthropic SDK + Claude Agent SDK
Runtime	Bun
Build	Vite 7
CI/CD	GitHub Actions

Scripts

Command	Description
bun --bun run dev	Start web dev server (port 3000)
bun --bun run build	Production web build
bun --bun run preview	Preview production build
bun --bun run test	Run tests (Vitest)
npx tsc --noEmit	Type check
bun run electron:dev	Vite + Electron dev
bun run electron:compile	Compile electron/ with esbuild
bun run electron:build	Full Electron package

Project Structure

src/
  canvas/              # Fabric.js canvas engine (29 files)
  variables/           # Design variables system (resolve, replace refs)
  components/
    editor/            # Editor layout, toolbar, tool buttons, top bar, status bar
    panels/            # Layer, property, AI chat, code, variables, export panels (24 files)
    shared/            # ColorPicker, NumberInput, VariablePicker, dialogs
    icons/             # Provider logos (Claude, OpenAI, OpenCode)
    ui/                # shadcn/ui primitives
  hooks/               # Keyboard shortcuts
  lib/                 # Utility functions (cn class merging)
  services/
    ai/                # AI chat, orchestrator, design generation, prompts (18 files)
    codegen/           # React+Tailwind, HTML+CSS, CSS variables generators
  stores/              # Zustand stores (7 files: canvas, document, history, AI, agent-settings, uikit)
  types/               # PenDocument/PenNode types, styles, variables, agent settings
  utils/               # File operations, export, SVG parser, normalization
  uikit/               # UI kit system (built-in registry, import/export)
  mcp/                 # MCP server integration (tools, document manager)
  routes/              # TanStack Router pages (/, /editor)
electron/
  main.ts              # Electron main process
  preload.ts           # Context bridge for renderer ↔ main IPC
server/
  api/ai/              # Nitro API: streaming chat, generation, agent connection, validation
  utils/               # Claude CLI resolver, OpenCode client, Codex client

CI / CD

CI (ci.yml)

Runs on every push and PR:

1. Type check (tsc --noEmit) + unit tests (vitest)
2. Production web build, uploads .output/ as artifact

Electron Builds (build-electron.yml)

Triggered by version tags (v*) or manual dispatch:

1. Parallel matrix build: macOS (.dmg + .zip), Windows (.exe), Linux (.AppImage + .deb)
2. Creates a draft GitHub Release with all platform artifacts

git tag v0.1.0
git push origin v0.1.0

Contributing

Contributions are welcome! Here's how to get started:

1. Fork the repository
2. Create a branch for your feature or fix: git checkout -b feat/my-feature
3. Make your changes — follow the code style in CLAUDE.md
4. Run checks before committing:

   npx tsc --noEmit    # Type check
   bun --bun run test   # Tests
   bun --bun run build  # Build
   

5. Commit with Conventional Commits format:

   feat(canvas): add multi-select rotation support
   

6. Open a Pull Request against the v0.0.1 branch

Code Style

• Files must not exceed 800 lines — split into focused modules when they grow
• One component per file, single responsibility
• File names in kebab-case: canvas-store.ts, use-keyboard-shortcuts.ts
• Use shadcn/ui design tokens (bg-card, text-foreground) — no hardcoded Tailwind colors

Roadmap

• Design variables / tokens with CSS sync
• Component system (reusable components with instances & overrides)
• AI-powered design generation with orchestrator
• MCP server integration
• Boolean operations (union, subtract, intersect)
• Multi-page support
• Collaborative editing
• Plugin system

License

MIT — Copyright (c) 2026 ZSeven—W