The memorysplice editor is simply a template for Ctrlr and since Ctrlr has some kind of VST support, he didn't have to figure out himself how to write a VST version (but according to the video tutorial it seems it does not even work with every DAW, apparently only Ableton on Windows is officially supported).
That said I was told by somebody who uses both the memorysplice editor and the JDXi Manager, that the memorysplice editor allegedly lacks other basic features such as saving and loading patches to and from files.
Whether that's worth $60 to you is your decision.
I actually started writing the JDXi Manager because I personally thought $60 was way too much for an editor. If it had been no more than $20 then I would have bought the memsplice editor and never written the JDXi Manager.
electrotecha wrote:i'm pretty shure that SDK VST it's free from steinberg.
The SDK is free (no cost) but using it in a closed-source product (such as the JDXi Manager) requires signing a contract with Steinberg.
Besides that, I looked into it in the past but could not find
any tutorial anywhere how to use the VST API for MIDI (there are only tutorials and examples for how to write
audio VST plugins).