.NET (SDK/Runtime) has always been free, but it's also been Open Source for several years now whilst F# has basically always been OSS and is stewarded by the no

.NET (SDK/Runtime) has always been free, but it's also been Open Source for several years now whilst F# has basically always been OSS and is stewarded by the non-profit F# Software Foundation. Microsoft will never charge for usage of .NET simply because that's not their business model which relies on mainstream adoption, previously it was to spur sales of Windows Desktop, Servers & their Infrastructure software but now with Azure they're happy for it to have ubiquitous adoption on Linux or Windows servers as well.