Springy is a force directed graph layout algorithm. It means that springy uses some real world physics to try and figure out how to show a network graph in a way that looks good.
Springy.js is designed to be small and simple. It provides an abstraction for graph manipulation and for calculating the layout and not too much else. The details of drawing and interaction are mostly up to you. This means you can use canvas, SVG, WebGL, or even just plain old positioned HTML elements.