We maintain container images for both Linux and Windows. I can tell you that they both get a LOT of use (>10M pulls/month). .NET is very much a cross-platform app stack. Also, we get plenty of bug reports on Linux (which we diligently fix). The days of .NET being Windows-only (and closed source) are long over.

>Almost all .NET developers I know still use Windows even on cloud

That seems untrue. On the Cloud side every .Net shop I know from startups to government/enterprise are now deploying to Linux or Linux containers.

On the developer side 75% of .Net devs are on Visual Studio on Windows but a big and fast growing segment are using JetBrains Rider on Mac/Ubuntu.

Yeah the comments show that you are right. It was wrong to make an assumption based on my small sample set.

We use .NET on Linux cloud for some years. Even on Windows we use Docker instead

I was talking with a Microsoft employee that works in azure. Something like 60% of their VMs are Linux.

How much of that 60% is running .NET apps, though?

Not everyone who uses Azure is a "Microsoft shop", in terms of programming tech stack. Plenty of people use Azure as a cross-cloud redundancy play, or because they do business with Amazon competitors that refuse to have their data on AWS.

My understanding is that a growing percentage of that is .NET. Even "big corporate" realizes .NET Linux deployments on Azure are cheaper and are trying to cost-cut/cost-save. There's still a small feature parity difference in Azure between Linux and Windows servers, primarily in my experience in "no touch" Application Insights telemetry/logging for application state (and user) monitoring as a major one. If that feature gap closed I expect that 40% to drop rapidly in Azure simply for cost cutting reasons. Anecdotally, I've been feeling internal pressure in my company to move .NET deployments to Linux servers for cost savings and we've done some initial trial balloons on the engineering effort for working around that feature gap.

I met a guy a while back who did stints for both Amazon and Azure orgs.

It's the reverse in AWS, they have a bit more Windows market share than Linux. And he also backed up your statement.

His take (which was just his speculation) was that the virtualization stacks ran those OS's more efficiently. HyperV with Linux VM's and KVM with Windows VM's. I have no idea if that's true or not.

I work in games so it's Unity C# (which uses a Mono port but .net 6 'soon') and a backend that uses .net in a linux container. Using C# on both makes it easier for devs to work full stack. It's been easy to run the backend app in k8s.

I've moved Windows Server into contained status at my organization and will not accept new software that required a Windows Server to run.

If you plan on shipping server software, I expect it to run on Linux, particularly in a container.

At least 95% of our .NET workloads run on Linux.

oh boy! It seems I was wrong all along. thanks all for the replies

Which OS are the developers using to write the code?

I personally use macOS and WSL2

I've been developing ASP.NET Core Apps on Windows since 2017 (when .NET Core support was added to our FX) and have created & deployed >50 .NET Apps exclusively to Linux, primarily Ubuntu so this is a welcomed announcement.

.NET definitely has first-class support on both Linux and Windows.

Used .NET (Framework) since version 2.0 released 15 years ago. Been running on Linux since .NET Core 1.0 became available.

Might this gain them marginal .NET developers? Maybe they have reason to believe that this will accelerate growth.

I've shipped .NET applications in organizations where adding Windows hosts never would have been contemplated, but adding a new application framework that ran on our standardized Linux environments was no big deal. Ops folks are often much warier about adding heterogeneous compute environments than they are about adding new application architectures, so an easier onboarding process for Linux shops experimenting with .NET could plausibly drive adoption.

I’m not sure but, it is nice to be able to install things without having to add additional repositories.

Been running .NET on Linux for years and develop with it on Mac, great experience.

We use linux for everything