Mondrian
Web-based vector graphics editor
...The interface favors direct manipulation—click, drag, resize, recolor—over menus and tool overload, so newcomers can produce striking designs quickly. Under the hood, it uses standard web tech to render shapes and support undo/redo, export, and sharing. Because it’s self-contained and open, it doubles as a learning resource for anyone curious about building interactive graphics editors in the browser. Designers and students use it for quick studies, poster drafts, and experiments with rhythm, contrast, and proportion.