I recently found this:
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It's a free virtual eurorack, currently in beta, that works as as standalone. Sources are available too, so if you are into C++ programming you might be interested. You can download it for Windows, macOS and Linux platforms.
I was curious about modular synthesis so I gave it a try (cause its free...), and if you know your basic of sound synthesis, it is really easy to use. Plus, you can find really good tutorials on youtube.
The only drawbacks are that for the moment you can't use it in your DAW as a VST (this feature is coming soon apparently), and there is no midi mapping (except for a keyboard), so once your patch is ready, if you want to play a little bit with the knobs, you got to do everything with the mouse... But hey, it's beta!
I'm not a specialist of modular systems so I can't compare the sound of VCV to real Eurorack systems, but all the module are based on real world modules, and to me, that sounds great.
Finally I can get those random blip blips and zbouibilliby without spending all my money!