VirtualMIDISynth!

Virtual MIDI Piano Keyboard is a MIDI events generator and receiver. It doesn't produce any sound by itself, but can be used to drive a MIDI synthesizer (either hardware or software, internal or external). You can use the computer's keyboard to play MIDI notes, and also the mouse. You can use the Virtual MIDI Piano Keyboard to display the played MIDI notes from another instrument or MIDI file player. To do so, connect the other MIDI port to the input port of VMPK.VMPK has been tested in Linux, Windows and Mac OSX, but maybe you can build it also in other systems. If so, please drop a mail to the author. »

FreePiano is a virtual MIDI keyboard and a VST host for windows.You can use freepiano to Play piano with computer keyboard or MIDI keyboard with any vst instrument you like, or output through MIDI.Or generate any MIDI message with any key on the keyboard.You can also record your song and export a MP4 movie to share with your friends.

TiMidity++ is an open source MIDI to WAVE converter and player.

The BASSMIDI MIDI synthesizer driver is a freeware SoundFont based Windows MIDI system driver (created by kode54 and Mudlord) for Windows XP, Windows Vista, and Windows 7. It uses the BASS and BASSMIDI audio libraries by Ian Luck (Un4seen Developments) as the SoundFont synthesizer, and includes a BASSMIDI Driver Configuration Utility, as well as a SoundFont Packer Utility.

SynthFont is a program for playing midi files using SoundFonts. It can also include VST instruments. Midi input for live playback is also supported.

Use this application to simulate playing a piano on your PC keyboard and enjoy learning chores and the note layout using the available songs.

Qsynth is a simple Qt4 application wrapper for the FluidSynth software MIDI sequencer for Linux.Qsynth is a fluidsynth GUI front-end application written in C++ around the Qt4 toolkit using Qt Designer. Eventually it may evolve into a softsynth management application allowing the user to control and manage a variety of command line softsynth but for the moment it wraps the excellent FluidSynth. FluidSynth is a command line software synthesiser based on the Soundfont specification. »

MidiKeys is a small application for Mac OS X that presents a miniature MIDI keyboard onscreen. You can use the computer keyboard to play MIDI notes, or click on the keys with the mouse. There is also an option to select a MIDI source and see incoming notes played on the keyboard.