Created by Yes Fitness Music, Tempo Magic is my favorite tempo app by far! Unfortunately it is only currently available on Apple products but if you have an Android, no worries. I've got an app for you too! You can check it out here.
With Tempo Magic, you can alter single tracks or full on music mixes, and the great thing is that it won't affect the pitch! If using a variety of single tracks, you can even lock the BPM so that each track has the same BPM. I LOVE using this in my circuit-style classes. During the cardio portions of my class I'll speed the tempo up to about 150+ bpm and during the strength or body weight strength portion of the class I'll turn the tempo back down to about 135 bpm.
Not only is this app great for classes, but it's great for running or even cycling! I love using this app on my runs. I'm so musically inclined that the beat means everything to me! I'll set my running tempo to 155 - 160 bpm and it keeps me on pace the whole time.
There is a basic and pro version of the app. The pro version costs $5.99 but if you're using it for your classes then it's totally worth the investment. You can download the app from the Apple Store here.
Have any questions or feedback about Tempo Magic? Comment below!