YUI Library – opensource
jQuery – MIT License
MooTools – Opensource MIT license
Backbone.js – Opensource
Backbone provide structure for web applications. Its a MVC framework.
Angular JS – MIT License
Angular JS is a best one to write client side web applications for smart browsers. You can make client side form validation, navigation, using Angular JS.
Ember – opensource
Knockout – opensource (MIT license)
Provide lot of functional programming support.
Meteor – Opensource
Script.aculo.us is a best add on for Prototype framework. You can create animation effects, drag and drop functions and ajax controls using Script.aculo.us.
Ext JS (commercial license)
qooxdoo – You can build websites. mobile application, single page web applications using qooxdoo.
Cappuccino – Better framework for Modern web development.
Durandal – MV architecture based SPA framework.
Glow – Apache licence. Glow provide simple DOM manipulation, animations, user interface widgets and event handling.
midorijs – Altra light weight framework. You can create pop up menus, auto complete & tabs selection using midori.
Raphaël – Best framework to create web graphics, animation & chart.
SproutCore – MVC framework. Provide build in tools to create great applications.
UIZE – UIZE provide templating system and code compression option to create better web application.
PureMVC – Easily create admin pages, Todo list with PureMVC.
eyeballs.js -Build tidy web application using eyeballs.js (MVC framework).
Sammy.js – Small web framework which include plugins and adapter systems.
Agility.js – You can write maintainable and reusable browser codes using Agility JS.
TrimJunction – Opensource junction framework. MVC framework.
CorMVC – jquery powered MVC framework.
Modernizr – Used to control HTML 5 and CSS3 features.
Maria – Another MVC framework.
Epitome -MVC (MVP) framework for moo tools.
PlastronJS – MVC pattern framework for closure library and compiler.
<rAppid:js /> – MVC framework.
Kendo UI – Commercial framework. Kendo UI mostly used in mobile application development.
Helma -Server side framework to develop websites and internet applications.
spludo -High performance serer side open source MVC framework.
grasshopper – Featured MVC framework built on node.js.