This app (or website) will tell you which note is sounding from your instrument! 

It is especially helpful for brass instruments: Trumpet, French horn, Trombone, Baritone, Tuba!

This website, will let you see the melodies you play. I like to use Hilbert Painter Visualization.

This app will also tell you what note you are playing. You can also record yourself playing and watch it after to see if you played the correct notes.

It is a little more complicated to use than Bandmate Tuner.