MIDI Tools

If you use a Mac, check out the tools available at https://www.snoize.com/.

Check out the fantastic tools created by Geert Bevin:

These two small tools are invaluable, and a must-have, if you do any kind of MIDI related development/debugging.

WebMIDI support

Check if your browser supports WebMIDI with WebMIDI.info.

https://www.snoize.com/MIDIMonitor/ MIDI Monitor is an app to display MIDI signals going in and out of your Mac.
https://www.snoize.com/SysExLibrarian/ SysEx Librarian is an app to let your Mac communicate with MIDI devices using System Exclusive messages, also known as SysEx. The most common use is to backup patch data from synthesizers, although there are others (such as sending firmware updates).
http://www.subtlesoft.square7.net/MidiPipe.html
https://www.johanlooijenga.com/tools/
https://www.morson.jp/pocketmidi-webpage/ Pocket MIDI is a MIDI monitoring tool for Windows and Mac. Connect your MIDI instrument to computer using a USB or USB/MIDI adapter and you can monitor MIDI messages to and from your instrument in real time. You can also send message from the application to your instrument. Pocket MIDI(for Windows/Mac) is a freeware.