Im not sure the type of training that you do but I deal mostly with folks trying to exercise to live pain-free, and everything is really centered around posture and movement qualify.
There two great apps if you do something similar.
The first is posture screen mobile. If it’s very cool because after you take pictures of your client it allows you to show exactly where deviations exist. The second app is from gray cook. He developed an app to use the functional movement screen and log your clients results.
Hope this helps,