What is e-Tube? And e-Tube Project software?
E-Tube is the name Shimano gave to their Di2 electronic communication system. It consists of electric wires, components, plugs and its own communication protocol (using CANBUS).
The e-Tube project software is the Windows desktop application Shimano released. You can use this software to set up your bike, customize settings and run diagnostics.
Shimano also released an iOS mobile/tablet app as well as Android versions. In order to use these mobile apps you’d need a Wireless Unit / D-fly or a System Information Display (XT / XTR).