A completely offline, smooth, modern PlantUML editor with bundled rendering engine
Open UML is a professional desktop application designed for creating PlantUML diagrams with zero setup required. Everything runs completely offline — the PlantUML rendering engine and Java runtime are bundled, so you can start creating diagrams immediately without any installation hassles.
Perfect for students, developers, and technical writers who need a reliable, fast, and beautiful tool for creating UML diagrams, flowcharts, and other PlantUML-supported diagrams.
- 🚀 Fully Offline - No internet connection required, all dependencies bundled
- ⚡ Lightning Fast - 300ms debounced rendering for instant preview updates
- 🎨 Modern UI - Beautiful, minimal interface with smooth animations
- 🌓 Theme Support - Dark and light themes with seamless switching
- 📝 Monaco Editor - Professional code editor with PlantUML syntax highlighting
- 🔍 Zoom & Pan - Zoom from 25% to 300% with Google Maps-style panning
- 💾 Export Options - Save diagrams as PNG or SVG
- ⌨️ Keyboard Shortcuts - Complete keyboard support for power users
- 📦 Cross-Platform - Windows and macOS installers available
- 🔒 Secure - Built with security best practices (context isolation, no node integration)
- Download
OpenUML-Setup-1.0.0.exefrom Releases - Run the installer
- Launch Open UML from the desktop shortcut or Start menu
- Start creating your PlantUML diagrams!
- Download
OpenUML-1.0.0.dmgfrom Releases - Open the DMG file and drag Open UML to Applications
- Launch from Applications or Spotlight
- If you see a security warning, go to System Preferences → Security & Privacy → Allow
- Live Rendering - See your diagrams update in real-time as you type (300ms debounce)
- Full PlantUML Support - All diagram types supported:
- Sequence Diagrams
- Class Diagrams
- Activity Diagrams
- Use Case Diagrams
- Component Diagrams
- State Diagrams
- And more!
- Export Options - Save your diagrams as:
- PNG (raster format, perfect for presentations)
- SVG (vector format, perfect for documentation)
- File Operations:
- New file (
Ctrl+N) - Open file (
Ctrl+O) - Save file (
Ctrl+S) - Save As (
Ctrl+Shift+S)
- New file (
- Error Detection - Automatic error parsing with line numbers and helpful messages
- Smooth Performance - 60 FPS UI with no lag during editing
- Fast Rendering - Typical diagrams render in <1 second
- Intuitive Interface - Split-pane editor and preview with resizable divider
- Zoom Controls - Zoom from 25% to 300% with smooth scaling
- Pan Support - When zoomed in, drag to pan around the diagram (like Google Maps)
- Persistent State - Auto-saves your work to localStorage
- Theme Toggle - Switch between dark and light themes instantly
- Responsive Layout - Works perfectly on all screen sizes
| Shortcut | Action |
|---|---|
Ctrl+N / Cmd+N |
New file |
Ctrl+O / Cmd+O |
Open file |
Ctrl+S / Cmd+S |
Save file |
Ctrl+Shift+S / Cmd+Shift+S |
Save As |
Ctrl+Shift+R / Cmd+Shift+R |
Render diagram |
Ctrl+Shift+G / Cmd+Shift+G |
Export as SVG |
Ctrl+Shift+P / Cmd+Shift+P |
Export as PNG |
- File Menu:
- New, Open, Save, Save As
- Render, Export as SVG, Export as PNG
- Help Menu:
- FAQ (links to GitHub repository)
- Contact (opens email client)
- Node.js 20+ and npm
- Git
-
Clone the repository
git clone https://github.com/choksi2212/open-uml.git cd open-uml -
Install dependencies
npm install
-
Set up PlantUML and JRE
You need to download and place the following in
app/plantuml/:plantuml.jar— Download from PlantUML releasesjre/— Extract OpenJDK 17+ JRE for your platform
Structure:
app/plantuml/ ├── plantuml.jar └── jre/ └── bin/ └── java (or java.exe on Windows) -
Run in development mode
npm run electron:dev
| Command | Description |
|---|---|
npm run dev |
Start Vite dev server only |
npm run electron:dev |
Start Electron + React dev mode |
npm run build |
Build production files |
npm run dist |
Generate installers (.exe/.dmg) |
npm run lint |
Lint TypeScript/React code |
open-uml/
├── app/
│ ├── main/ # Electron main process
│ │ └── index.ts # Window creation, IPC handlers
│ ├── renderer/ # React UI components
│ │ ├── App.tsx # Main app component
│ │ ├── components/ # UI components
│ │ │ ├── Editor.tsx # Monaco editor wrapper
│ │ │ ├── Preview.tsx # Diagram preview with zoom/pan
│ │ │ ├── TopBar.tsx # Top navigation bar
│ │ │ └── ErrorPanel.tsx # Error display
│ │ └── index.css # Global styles
│ ├── assets/ # Icons, logos
│ ├── plantuml/ # plantuml.jar + JRE
│ └── preload.ts # IPC bridge
├── .github/
│ └── workflows/ # CI/CD workflows
│ └── release.yml # Automated releases
├── build/ # Build output (installers)
├── dist/ # Production build
├── dist-electron/ # Electron build output
├── package.json
├── electron-builder.yml
└── README.md
- ✅ Rendering speed: <1s for typical diagrams
- ✅ UI FPS: ≥60
- ✅ No stutters or visual lag
- ✅ Fully offline operation
- ✅ Memory-safe subprocess handling
- ✅ Full PlantUML compatibility
- ✅ Installer size: ~200 MB (includes Electron, Chromium, PlantUML, and JRE)
Contributions are welcome! Please follow these steps:
- Fork the repository
- Create a feature branch (
git checkout -b feature/amazing-feature) - Commit your changes (
git commit -m 'feat: add amazing feature') - Push to the branch (
git push origin feature/amazing-feature) - Open a Pull Request
Follow Conventional Commits:
feat:— New featurefix:— Bug fixdocs:— Documentationstyle:— Code stylerefactor:— Code refactoringtest:— Testschore:— Maintenance
This project is licensed under the MIT License — see the LICENSE file for details.
- PlantUML — The amazing diagramming language
- Electron — Cross-platform desktop framework
- Monaco Editor — Code editor
- React — UI library
- Tailwind CSS — Styling framework
- Vite — Build tool
Created for Students by Manas Choksi with ❤️
