A simple, free, ready-to-go wavescope made with MaxForLive.
You can visualize 2 different inputs simultaneously on top of each other, and you can also pay-what-you-want.
Max 8.1.6 minimum is required.
(as always, I advise you to use a valid email address so you won't miss future device updates - I don't spam... Once in a while I send an absurd email, but that's it)