The source of Kerfstok can be downloaded from this url: https://github.com/j-kaltes/Kerfstok
For more information about Kerfstok see: https://www.juggluco.nl/Kerfstok/index.html
You can install a compiled version of Kerfstok from: https://apps.garmin.com/en-UK/apps/b6348ccc-86d8-4780-8013-d9e19fed5260
I allow everyone to modify the source of Kerfstok as they like.
You can also send bug reports, modifications or additions.