It is an LGPL- and/or EPL-licensed client-side and server-agnostic solution, and includes support for professional JavaScript development, a graphical user interface (GUI) toolkit and high-level client-server communication.

Most modern browsers are supported, including Gecko (Firefox, Mozilla, SeaMonkey), Presto (Opera), Trident (Internet Explorer, RealPlayer, Winamp), WebKit (Chrome, Safari).

Among the accompanying toolset is a comprehensive JavaScript parser that is an integral part of the automatic build process and is used to optimize, compress, link and deploy custom applications, and generate documentation.

Simple appearance themes are used to style colors, icons and other visual properties; they also support runtime switching.. qooxdoo uses a closed form to define new classes.

While being a client-side and server-agnostic solution, the qooxdoo project does include optional RPC server implementations (currently in Java, PHP, Perl and Python) to demonstrate client-server communication.