It was pretty much always open source and cross platform. The original version wasn't even developed on windows: https://github.com/SSCLI/sscli20_20060311 https

It was pretty much always open source and cross platform. The original version wasn't even developed on windows: https://github.com/SSCLI/sscli20_20060311 https://github.com/SSCLI/sscli20_20060311 Although being open source and free doesn't necessarily make it open and accessible. The core CLR team do not listen to customers, particularly ones who complain about not wanting telemetry by default in there, ones who open bugs in the HTTP stack which spam logs for months and months and months and complete deadlocks and crashes. Open Source has only completely absolved Microsoft of any responsibility to support their products to actual paying customers, who are told to open github issues now which are auto-closed after being ignored. I'd rather invest my time in any other platform without the other issues that it brings at this point.