openpencil
The world's first open-source AI-native vector design tool and the first to feature concurrent Agent Teams. Design-as-Code. Turn prompts into UI directly on the live canvas. A modern alternative to Pencil.
OpenPencil is an open-source AI-native vector design tool with a built-in MCP server that enables AI agents to create and modify UI designs programmatically. The MCP server provides tools for reading, creating, and modifying .op design files through any MCP-compatible agent like Claude Code, Codex, or Copilot CLI. It features a layered design workflow (design_skeleton → design_content → design_refine), segmented prompt retrieval, and style guide tools. The server runs via stdio transport through the desktop binary or as a live HTTP endpoint, requiring no Node.js runtime.
Key Features
Use Cases
- 01Automate UI design generation from natural language prompts in terminal workflows
- 02Generate multi-section landing pages with skeleton-first, content-second workflows
- 03Apply consistent visual styles (glassmorphism, brutalist, retro) to AI-generated designs
- 04Modify existing .op design files programmatically through agent conversations
- 05Integrate design workflows into CLI-based development environments
- 06Create and manage multi-page design documents via MCP tools
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openpencil — FAQ
What is the OpenPencil MCP server?+
The OpenPencil MCP server is a built-in component that exposes design automation tools to MCP-compatible AI agents. It allows agents to read, create, and modify .op design files through a layered workflow, enabling programmatic UI generation from natural language prompts.
How do I install the OpenPencil MCP server?+
Install the desktop app via Homebrew (brew install --cask openpencil) or download from GitHub Releases. Then add the MCP server configuration to your Claude Code, Codex, or other MCP client config, pointing to the openpencil-desktop binary with the --mcp flag and your .op file path.
Which AI clients work with OpenPencil MCP server?+
The MCP server works with Claude Code, Codex CLI, OpenCode, Kiro, GitHub Copilot CLI, and any other MCP-compatible agent or client.
Do I need API keys or prerequisites to use the MCP server?+
You need the OpenPencil desktop application installed. No additional API keys are required for the MCP server itself, though AI-driven design features require configuring an AI provider (Anthropic, OpenAI, Google, etc.) in the application settings.
Is the OpenPencil MCP server free?+
Yes, OpenPencil and its MCP server are free and open-source under the MIT license.
Can the MCP server run without the desktop UI?+
Yes, you can run a headless file-backed server with 'openpencil-desktop --headless --file design.op' or use the CLI tool 'op' for terminal-based design control.
How do I install openpencil?+
Open the source repository on GitHub and follow its README. openpencil is a mcp server — MCP Agents Market links you directly to the official repo.
Is openpencil free?+
openpencil is an open-source project hosted on GitHub. Check the repository for its license and any usage requirements.