It's free to use and open source, was developed for my own use, thought I'd release it and make it public as others might get some use out of it.

It allows you to set a per key curve and or global curve for your keyboards.
It also has a calibration which is useful for when you have keys producing higher or lower velocities than they should, like my own Kawai MP11SE.
To calibrate you basically aim to reproduce the lowest up to the highest velocities, using something straight edged, more info about it on the github.

Most of the testing was done on Windows, the app loads fine on Linux and Mac which was confirmed today.
It has both Standalone and VST3, it also has AU for Logic on the Mac which lets you use it for Midi FX.

Any issues or questions, go ahead and create an issue post on github.

https://github.com/SH4DOWSIX/VelCal