GSAP!

KUTE.js is a complete Javascript animation engine with outstanding performance and supporting 3D transforms, SVG Morph, draw SVG, SVG transform, cross-browser animation, scroll animation, CSS3 properties and many more.

Anime.js is a JavaScript animation engine.

Animate.css is a bunch of cool, fun, and cross-browser animations for you to use in your projects. Great for emphasis, home pages, sliders, and general just-add-water-awesomeness.

The world of banner ad creation has changed a lot. With Flash not being accepted anymore, you need a proper solution for supplying creative digital ads. Animated GIFs don’t quite cut it. And hand coding countless banners can be time consuming, expensive – and, let’s be honest, right on the edge of most designers’ skillset.

Create super-smooth CSS transitions and do interesting transformations using jQuery.

Popmotion is a lightweight 12kb JavaScript motion engine that makes creating engaging user interactions quick and simple.

txt.wav provides some weird text animations the internet deserves.

Velocity.js: An incredibly fast animation engine for motion designers.