Welcome to SimpleMermaid, a free real-time Mermaid.js editor for creating flowcharts, sequence diagrams, Gantt charts, class diagrams, state diagrams, entity relationship diagrams, and more. Write your diagram code on the left, see it render instantly on the right. No account required, and your diagrams never leave your browser.
Your diagram renders as you type with live syntax validation and instant visual feedback.
Click Share to generate a URL that contains your entire diagram. Recipients see your diagram immediately, no account needed.
Export to PNG for presentations, SVG for scalable graphics, or PDF for documentation. All exports are high-resolution.
Choose from architecture diagrams, security threat models, project management charts, and more from the dropdown above.
Quick start: Select a category and example from the dropdowns above, or start typing Mermaid syntax in the editor. Try flowchart TD to begin a top-down flowchart. Use the toolbar buttons to save, share, copy, and export your work.
Keyboard shortcuts: Ctrl+T new tab, Ctrl+S save, Ctrl+W close tab, Ctrl+Tab cycle tabs.
SimpleMermaid supports all Mermaid.js diagram types including flowcharts, sequence diagrams, class diagrams, state diagrams, entity relationship diagrams, Gantt charts, pie charts, and user journey maps. The editor features dark mode for comfortable extended use, horizontal and vertical layout modes, resizable panels, and real-time syntax error reporting. All processing happens locally in your browser with no server-side dependencies, making it completely private and offline-capable.
