GraphvizOnline is a client-side Single Page Application (SPA) designed for editing and rendering Graphviz DOT language diagrams directly within the browser. The architecture is purely frontend, utilizing the Ace Editor library for syntax highlighting and `viz.js` (Graphviz compiled to JavaScript/WebAssembly) for rendering. The application manages state via URL parameters and hash fragments, enabling shareable links and presentation modes without backend dependencies. It functions as a self-contained static web tool, relying on bundled dependencies for core functionality.