MochiKit

Web site: http://mochikit.com/

License: MIT or Academic Free License, v. 2.1

MochiKit is a complete JavaScript library that is designed to be a base for building rich Web applications. Features include visual effects, drag-and-drop support, JSON serialization and safe evaluation, string and date formatting, event management, and a number of other development tools. AJAX communication support is focused on JSON and supports only asynchronous operation. The library is well documented at the API level, but there is little high-level documentation explaining how it all fits together. Although MochiKit is a large library, it takes strides to be well name-spaced so that it can be used with other libraries.