Fabric.js

Fabric.js keeps an object model on top of the canvas: every rectangle, circle, path, text box or image is an object with properties, and the library draws selection handles and takes care of dragging, scaling, rotation, grouping, layering and free drawing with brushes. It imports and exports SVG and can save a whole scene as JSON to load again later, which is what design tools need.

Typical uses are T-shirt and product customisers, banner and meme makers, whiteboards, image annotation and certificate or label designers. It runs in the browser and, through node-canvas, in Node for rendering on a server. Konva is a similar library with official React bindings (react-konva); for 3D, Three.js is the usual choice.