Geon Kick
Free and Open Source (the github is here), but they charge EUR15 for a pre-built binary on the homepage. Naturally this funds the project, and the source is available, so I presume you can build the full version for yourself if you're so inclined. Given the time involved, you're probably saving yourself a few pounds per hour, so paying makes sense.
Youtube Tutorials
Free Software But EUR15?
This is an example of how Free Software may not be gratis: you may charge what you like for distributing the software to somebody, and that is your right. But once you distribute, the recipient gets all the same GPL rights you had. So you could build the binary yourself and distribute that gratis, which is effectively what the Ubuntu repo does. But frankly I'd rather let the author take their EUR15 each time. It's a worthwhile tip for a developer.
Ubuntu
Note that there is a geonkick package in the Ubuntu 24.10 repo.
So sudo apt install geonkick does the trick.