Keppy's MIDI Converter (informally called Keppy's Converter or KMC) is an actively-developed MIDI-to-Audio converter/renderer developed by KaleidonKep99 for Windows. It can convert many MIDIs into audio. Unlike many converters, Keppy's Converter was built from the ground up for the purpose of black MIDI use (in addition to normal MIDI conversion); as such, it is extremely efficient, fast, and widely-tauted as a great converter. The converter comes in two versions, supporting two architectures: x86 and x64, which are both downloaded with every release. The program itself is open source, and is based off of the BASS libraries.


Keppy's MIDI Converter showing the main window, on Windows 10

Unlike some other MIDI converters, Keppy's Converter has the ability to batch convert MIDIs -- in other words, one can choose to load multiple MIDIs and all of them would be converted one by one. In addition to batch conversion, Keppy's Converter does not preload MIDIs in conversion -- rather, it streams events out of the MIDI in realtime which makes for a lightweight conversion that can work with even the largest of MIDIs (it is theorized that the limit of the converter is above 500 million notes when the x64 version is used). 

Both the source and the executable file can be downloaded from here: GitHub Release Page

Development history

  • As of September 2015, it is actively developed by an experienced Black MIDI Team member; it serves as one of the only programs developed within the team itself.
  • On November 7th, 2015, development is switched from VB.NET to C#, and the converter has been rebuilt from scratch. Its source code is released.
  • On August 5th, 2016, the converter got support for VST effects.
  • On August 7th, 2016, the converter got support for Linux and Mac OS X through its Java version, translated from C# by TheGhastModding.
  • On August 16th, 2016, the converter got support for multiple languages.
  • On September 26th, 2016, the converter got support for real-time audio simulation (Simulate PFA 's playback with a synthesizer).
  • On December 28th, 2016, the converter got the ability to real-time simulate MIDIs with more than 40 million notes.
  • On August 19th, 2017, the converter got the ability to change the position in preview mode.
  • On March 4th, 2018, the converter got an huge performance boost, thanks to the complete rewrite of the source code by KaleidonKep99. The source code of other major components has also been rewritten.
  • On March 8th, 2018, its support for VST instruments improved.



Keppy's MIDI Converter's VST manager, on Windows 8.1

  • Written in C#.
  • Easy to use.
  • Batch MIDI support.
  • Real-time MIDI streaming.* (It doesn't load the MIDI in memory)
  • Real-time audio simulation.
  • Supports various soundfont formats, such as:
  • Supports up to 100,000 voices and frequencies up to 192kHz.
  • Exports 32-bit floating point WAV files, for the maximum audio fidelity. (It can also export 32-bit floating point OGG Vorbis files)

*Except when using the real-time audio simulation.

Pros and cons


  • It's free, unlike most of its alternative online.
  • It's fast and lightweight.
  • It (theoretically) has no MIDI size limit in the 64-bit compiled app.
  • It has full VST2 support.


  • It constantly gets updated, meaning it's not a full-done work. It might be unstable. (Not a thing since version 17.0.0)
  • The playback mode isn't the best for Black MIDI playback. It's susceptible to note strums. (Fixed as of version 16.0.9)


For the changelog, visit the official GitHub download page here: Releases · KaleidonKep99/Keppys-MIDI-Converter