We did Dance Mat which is free but the problem with that was that it didn’t save my son’s work (9 yrs old). I tried to find other free programs but none would allow me to choose which keys I wanted him to work on at that time (like the home row keys only).
We are also now using Typing Instructor for Kids Platinum and he is having a lot of fun and doing very well with it. It saves your progress, you can set what the goal words per minute will be and what keys he can work on, has reports that show WPM on each finger or hand, etc. We downloaded it from Amazon for, I think $15, or you can buy the CD for $20. Hope that helps!