Name : JOSM (Java Open Street Map Editor)
Homepage : https://josm.openstreetmap.de/
Reason : JOSM is a very powerful editor for OpenStreetMap. It can be a little complicated to get working for non-technical users. It would be nice to allow easy install of the programme via the Software Centre, to make it more accessible to end users.
Open Source : Yes (GNU General Public License v2 or later)
Source Code : There are different methods, more details here -https://josm.openstreetmap.de/wiki/Source%20code#Getthesource