Here are the requirements for developing and deploying with qx.Desktop. Applications built with it run in a web browser, so you need at least one of the supported browsers to check your work. During development time you will also need the tools from qooxdoo's SDK to create runnable versions of your application. But these tools are not necessary once you have deployed it.
The cross-browser abstraction of qooxdoo not only benefits the users of your application, it allows also you as a developer to pick your preferred development platform, i.e. combination of browser and operating system, and be confident that the result will run on all other supported platforms.
qx.Desktop does not enforce any specific backend components, any server that is reachable through its I/O layer should be fine. During development, loading your application from the file system should suffice, as long as your application logic doesn't enforce a server connection. Developers should note, though, that with some browsers, such as Chrome and Firefox, there is a known constraint when loading reasonably complex qooxdoo applications (such as the APIviewer or the Demobrowser) via the file:// protocol. Either consult your browser's documentation (usually there is a command-line option to change this), or use the HTTP protocol during development. In the latter case be sure to read and understand this FAQ entry.
An application comprising of the qooxdoo runtime and custom code written against its API runs across all modern web browsers, unaltered, and with mostly identical look & feel:
|Internet Explorer 8+|
Older versions should generally work but we can't guarantee that there aren't any problems.