CogTool is a general purpose UI prototyping tool with a difference--
it automatically evaluates your design with a predictive human
performance model (a "cognitive crash dummy"). Simply create a
storyboard of your design idea with sketches, images or on a canvas
with CogTool's widgets, demonstrate tasks on that storyboard, then
press a button to produce a valid cognitive model predicting how long
it will take a skilled user to complete those tasks. CogTool can be
used today to baseline your current interface, or compare competitors'
interfaces, and predict how much better your new designs will be.

CogTool is free software, released under the FSF Lesser Gnu Public
License. See LGPL.txt for details.

The source code for CogTool is now (as of 9 December 2013) stored on
GitHub. To access it clone:

https://github.com/cogtool/cogtool.git

There is a separate repository of documentation, both for end users
and for developers:

https://github.com/cogtool/documentation.git

For building CogTool from source, see in particular

Processes/configuring-development-machines.txt