I was introduced to this app on HelloTalk.
I haven’t had much of a chance to try it out yet, but it does have impressive credentials, developed by the International University of Japan, both for their registered students and for non-students.
It has a nice reference page describing the different methods of language shadowing, and then you go to download lessons at your current level of Japanese fluency.
You can have the script used open, or you can hide it and just focus on shadowing the speech you hear.
It records your voice so you can compare your speech patterns to the patterns of the native speakers. This might be a problem for some, but I don’t mind it.
All in all, I’m pretty excited about this one!