OpenPencil

Why OpenPencil

🎨 Prompt → Canvas

Describe any UI in natural language. Watch it appear on the infinite canvas in real-time with streaming animation. Modify existing designs by selecting elements and chatting.

🤖 Concurrent Agent Teams

The orchestrator decomposes complex pages into spatial sub-tasks. Multiple AI agents work on different sections simultaneously — hero, features, footer — all streaming in parallel with per-member canvas indicators.

🧠 Multi-Model Intelligence

Automatically adapts to each model's capabilities. Claude gets full prompts with thinking; GPT-4o/Gemini disable thinking; smaller models (MiniMax, Qwen, Llama) get simplified prompts for reliable output.

🔌 MCP Server

One-click install into Claude Code, Codex, OpenCode, Kiro, or Copilot CLIs. Design from your terminal — read, create, and modify .op files through any MCP-compatible agent.

🎨 Style Guides

Built-in style guide library with tag-based fuzzy matching. Apply visual styles (glassmorphism, brutalist, retro, etc.) to AI-generated designs. MCP tools for external agent access.

📦 Design-as-Code

.op files are JSON — human-readable, Git-friendly, diffable. Design variables generate CSS custom properties. Code export to React + Tailwind or HTML + CSS.

🖥️ Runs Everywhere

Web app + native desktop on macOS, Windows, and Linux — one Rust core, a single self-contained binary, no browser engine. .op file association — double-click to open.

⌨️ CLI — op

Control the design tool from your terminal. op design, op insert — batch design DSL, node manipulation. Pipe in from files or stdin. Works with desktop app or web server.

🎯 Multi-Platform Code Export

Export to React + Tailwind, HTML + CSS, Vue, Svelte, Flutter, SwiftUI, Jetpack Compose, React Native — all from one .op file. Design variables become CSS custom properties.

🧩 Embeddable SDK

op-web-sdk (vanilla) + op-web-sdk-react / op-web-sdk-vue adapters — embed a read-only .op viewer in your own app, powered by the same wasm renderer the editor ships.

🛡️ Design System Kit

Manage reusable UIKits with style switching and component composition. Import/export kits from .pen files. Built-in registry with MCP tools for external access.

👥 Real-Time Collaboration

Design together over authenticated peer-to-peer sessions with a public relay and built-in regional hubs. Join with a short pairing code, see live remote cursors, and resolve conflicts with per-edit detail and replay.

Install

Building from source on Windows: see BUILD_WINDOWS.md

macOS (Homebrew):

brew tap zseven-w/openpencil
brew install --cask openpencil

Windows (Scoop):

scoop bucket add openpencil https://github.com/zseven-w/scoop-openpencil
scoop install openpencil

Linux / Windows direct download: GitHub Releases — .exe (Windows), .AppImage / .deb (Linux)

The Windows .exe installer, both Scoop packages, and the install-op.ps1 CLI installer check and, when needed, service the pinned, Microsoft-signed Visual C++ v14 runtime during every install or upgrade. The portable Windows .zip archives and Windows VSIX packages do not run an elevated system installer; install Microsoft's latest supported Visual C++ Redistributable before using those artifacts directly.

Antivirus flagged the Windows installer? That's a known heuristic false positive on new, low-prevalence releases — see how to verify your download.

Nix (Linux x86_64):

nix develop
nix run .                         # launch the desktop app
nix build .#openpencil            # native web host + CanvasKit web bundle
nix build .#op-cli                # the `op` CLI
nix build .#prebuilt              # use the matching upstream desktop archive
nix build .#prebuilt-cli          # use the matching upstream CLI archive
nix build .#web-server            # native GL-free web server + web bundle
nix build .#runtime-prebuilt      # prebuilt desktop + `op` CLI runtime
nix build .#web-sdk-packages      # npm tarballs for the web SDKs
nix build .#appimage              # portable desktop AppImage

The flake uses the pinned Rust toolchain from rust-toolchain.toml and is currently published for x86_64-linux. A Debian package is not produced by the flake yet; use the upstream release artifacts when a .deb is required. The prebuilt outputs use the release version and hashes pinned in nix/release-manifest.json, independently of the workspace source version. After a release is published, the release workflow opens a PR to refresh that manifest. Until it is merged, the prebuilt outputs continue to use the prior published release; the source-built outputs always build the checked-out source.

CLI (op):

brew install zseven-w/openpencil/op

Or use the install script (macOS / Linux):

curl -fsSL https://raw.githubusercontent.com/ZSeven-W/openpencil/main/scripts/install-op.sh | bash

To allow the newest pre-release:

curl -fsSL https://raw.githubusercontent.com/ZSeven-W/openpencil/main/scripts/install-op.sh | OP_PRERELEASE=1 bash

Windows PowerShell:

irm https://raw.githubusercontent.com/ZSeven-W/openpencil/main/scripts/install-op.ps1 | iex

To allow the newest pre-release:

$env:OP_PRERELEASE = "1"; irm https://raw.githubusercontent.com/ZSeven-W/openpencil/main/scripts/install-op.ps1 | iex

Cloning (with submodules)

git clone --recurse-submodules https://github.com/ZSeven-W/openpencil.git
# Or already cloned — sync first so stale submodule URLs pick up .gitmodules changes:
git submodule sync --recursive && git submodule update --init --recursive

This is the beginning of the README. Read the rest at the original. Read the full README ↗