[This is the english translation of the german article Wireframe-Tools]
Motivation: Reaching UI agility
One of the main goals of agile development is to improve the reaction to changes. Changing UI is expensive in term of time and resources. Indeed, UI changes do not only impact the UI layer, but may also require not planned features and architectural changes. To avoid too late changes, we propose, to our customers, prototypes of applications, tangible regarding interactions and UI design. Those prototypes are developed early in the development process, and so open discussion about the final UI.