PlantUML Editor
Write PlantUML diagram code and see a live SVG preview. Export as SVG or PNG. 100% client-side, nothing leaves your browser.
About This Tool
The PlantUML Editor is a free, browser-based tool for writing and previewing PlantUML diagrams without installing any software. Type PlantUML syntax in the left panel and see the rendered diagram appear instantly in the right panel. The editor supports the most common diagram types: sequence diagrams, class diagrams, activity diagrams, use case diagrams, component diagrams, state diagrams, deployment diagrams, and object diagrams.
The built-in template library provides starter code for each diagram type so you can quickly scaffold a new diagram and modify it to suit your needs. The editor includes line numbers, monospace font rendering, and a syntax quick-reference panel for looking up arrow notation, keywords, and block structures.
Once your diagram looks right, export it as SVG for vector-quality graphics in documentation or as PNG for embedding in presentations and chat messages. The copy-to-clipboard button lets you grab the raw SVG markup for pasting into HTML pages or design tools.
If you work with Mermaid syntax instead of PlantUML, try the Mermaid Diagram Editor which offers a similar live preview experience. For editing raw SVG paths, the SVG Path Editor gives you draggable control points. And if you want to convert diagrams into Markdown documentation, the Markdown Preview tool renders GFM in real time.
All processing runs entirely in your browser. Your diagram code is never sent to any external server. This makes the tool safe for proprietary architecture diagrams, internal system designs, and confidential project documentation.
How to Use
- Select a diagram template from the dropdown to load starter PlantUML code, or type your own code directly in the editor.
- Edit the PlantUML source in the left panel. Line numbers update automatically as you type.
- Watch the right panel update in real time to show the rendered diagram preview.
- Expand the Syntax Quick Reference section below the editor if you need to look up arrow types or keywords.
- Click Copy SVG or press Ctrl+Shift+C to copy the SVG markup to your clipboard.
- Click the SVG or PNG download button to save the diagram as a file.
- Click Clear to reset the editor and start a new diagram from scratch.
Popular PlantUML Examples
FAQ
Which PlantUML diagram types are supported?
The editor renders sequence diagrams, class diagrams, and activity diagrams with full visual SVG output. Use case, component, state, deployment, and object diagrams are rendered with syntax-highlighted code display. All diagram types can be written and exported.
Does this tool connect to PlantUML's online server?
No. All rendering is performed 100% client-side in your browser using built-in SVG generation. No diagram code or data is ever sent to any server, including plantuml.com. Your diagrams remain completely private.
Can I export diagrams as images?
Yes. You can export as SVG (vector format, ideal for documentation and web) or PNG (raster format, ideal for presentations and chat). The PNG export renders at 2x resolution for crisp output on high-DPI screens.
How do I use templates?
Click the template dropdown at the top of the editor and select a diagram type. The editor will load starter code that you can modify. Available templates include Sequence, Class, Activity, Use Case, Component, State, Deployment, and Object diagrams.
Is my data safe?
Yes. All processing runs entirely in your browser using JavaScript. No diagram source code, SVG output, or any other data is ever transmitted to any server. You can verify this by checking the Network tab in your browser's developer tools while using the tool.
What keyboard shortcuts are available?
Press Ctrl+Shift+C (Cmd+Shift+C on Mac) to copy the SVG output to your clipboard. Standard text editing shortcuts (Ctrl+A, Ctrl+Z, Ctrl+Y) work in the editor panel.
Can I embed the SVG output in my website?
Yes. Click Copy SVG to get the raw SVG markup, then paste it directly into your HTML. The SVG is self-contained with no external dependencies, so it will render correctly anywhere that supports inline SVG.
Related Tools
Mermaid Diagram Editor
Write Mermaid diagrams with live preview. Export as SVG or PNG. Supports flowcharts, sequence, ER, and more.
Markdown Preview
Write and preview Markdown in real time with GFM support, tables, task lists, and HTML export.
SVG Path Editor
Visually edit SVG path d attributes with draggable control points, command palette, bezier curve handles, and real-time preview.
ASCII Art Generator
Convert text to ASCII art using various font styles. Choose from multiple fonts, adjust width, and copy the result.
README Generator
Generate professional README.md files from a simple form. Choose templates, add badges, sections, and download instantly.