I love Freescout, Use it for multiple clients.
One downside is that the app is just the website on your phone and does not really work well.
It works but not as an App experience.
For the rest they do awesome and developing in it works good!
The best alternative to Helpscout, Helpwise or similar. Works great, and you don't need so much requirements on your server. There are a lot of then with an autoinstaller.
