GoJS - GoJS is a JavaScript library for building interactive diagrams on HTML web pages. Build apps with flowcharts, org charts, BPMN, UML, modeling, and other visual graph types.

mxGraph - mxGraph is a fully client side JavaScript diagramming library - jgraph/mxgraph

Konva - Konva is 2d Canvas JavaScript framework for drawings shapes, animations, node nesting, layering, filtering, event handling, drag and drop and much more.

jsPlumb - jsPlumb is an advanced, standards-compliant and easy to use JS library for building connectivity based applications, such as flowcharts, process flow diagrams, sequence diagrams, organisation charts, etc. More than just a diagram library.

Paper.js - Open source vector graphics scripting framework that runs on top of the HTML5 Canvas.

Three.js - A JavaScript 3D library which makes WebGL simpler.