License questions (VST2.4)

Hi All,

I am currently thinking about changing the MLVST PG-8X to an open-source license, and consider various options.

As a GPL license seems to be incompatible with VST2.4, I am wondering whether anybody is using IPlug2 for open source VST2.4, and what options I would have. It seems that IPlug2 itself is NOT under a GPL like license, so using IPlug2 would not force me to GPL the code (and hence exclude myself from VST2.4). I should add that I still do have the valid VST2.4 license I used for the current version of PG-8X.

As a side question: Are there any guides on how to port an Iplug/wdl-ol plugin to iplug2?


Hi Martin

Great news :slight_smile:

It would be very cool to have your PG8X as an example for an open source iPlug2 project. I think you could use GPL if you wanted to publish the source, but it would of course be nicer to have a more liberal license. VST2.4 is a dead format, so I wouldn’t worry about its license requirements.

There are some hints here Upgrading an iPlug1 project · iPlug2/iPlug2 Wiki · GitHub

I’d be happy to help you out on slack if you want a hand getting your codebase ported over.


Hi Oli,

Thanks for the response. Currently, I am not yet decided how to proceed. I had some people from the Surge Synth Team, offering help to port the project to JUCE, and I am sure you would be willing to help porting to IPlug2. I am currently looking at both frameworks, to see which is more suitable.

Regarding the VST2.4 format, I am a bit more worried. I do have a valid VST2.4 license, but clearly it would not be to publish a GPL plugin using VST2.4. JUCE seems to require GPL, if you want to stick with the free version. IPlug2 seems not to force that.

Personally, I would not mind too much about giving up VST2.4, but there have already been some worried replies on KVR where some people would not want to see the VST2.4 vanish, as there still seem to be some hosts (Ableton 9, I guess) which do not support VST3.

I will have a look at the link about porting a project. I tried the slack channel, but got a message that the link was out of date, What is the current name of the channel?


you can still build and distribute the VST2 version yourself since you have signed the agreement, and anyone who has the VST2 source can build it. What you can’t do is include the VST2 sdk in your github project.

iPlug2 is liberally licensed, it’s one of its best features :slight_smile:

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