Pocket MIDI 4+

I am developing a USB MIDI device which receives control messages from the computer and sends hardware user interface (knobs and buttons) changes back to the computer, and this sort of tool is really helpful.

Not only does it monitor MIDI IN messages to the computer (so you can see the messages sent from control changes), it can generate specific MIDI OUT messages. You wiggle the knob for a specific controller and the message sent to the device is shown. This is much easier than trying to wrangle Logic or Garage Band to send messages to see how the external device responds.

Yeah, I'd actually pay ten bucks for this.

I was looking for a way to connect a longer keyboard to control a shorter workstation but advanced keyboard and finally found this app to do it. I was able to set the MIDI In to the Yamaha Portable G keyboard and the Output to the Digital workstation and turned on the "Thru" option in between them in MIDI settings to make what the Yamaha Portable G keyboard plays reflect on the Digital Workstation. FINALLY!!!!

It does dump raw incoming MIDI messages as hex. Can't find a way to save the data to a binary MIDI file. Can't figure out how to capture outgoing MIDI from other apps (Arturia's MIDI Control Center.)
The UI is a mess - it's one window with several fake "windows", with real-looking title bars, inside it, like an old Windows MDI app. Clearly a quick port (it's using the awful cross-platform Qt framework.)
The Filter command is useful but unintuitive, since the items you check are filtered _out_ of the capture; this threw me for a loop.
Overall, I won't look a gift horse in the mouth, but this could really use some work.
UPDATE: I'd recommend MidiView instead, for basic MIDI dumps.