pocketOscilloscope

Easy to get free, but worth the $1 too. I know it isn't glamorous but it does the job and seemingly quite well from what I'm seeing. It is nice to see a straightforward utility plugin that's not a "vintage emulation" or providing "analog warmth" even though a lot of those have come a long way and can be very cool. Sometimes you just need to grab a tool and have it do its job simply. Oscilloscope does that, and is exactly what it says and does what it says on the tin.