I used to work for a .NET shop (pre .NET Core) doing F#, and we used IIS.
In the company Slack, I said something like "Serious question; is there something that IIS does better than something like Nginx or any other open source server?"
One of the most senior engineers responded back with "crashing".
IIS can be configured by non-expert users easily, and without necessarily compromising security, thanks to the well-designed (I’m being serious) administration tools that MS has (thankfully) not butchered-up over the past 15 years.
It’s an “old-world” web-server (like Apache, etc) which defaults to “filesystem-first” which is great for quickly making a directory available on the web, and its architecture employing recyclable worker-processes (since IIS 6) with limited privileges gives it the performance benefits of in-proc code-execution (vs CGI/FastCGI) without the risk of a vuln compromising the entire web server. Oh, and HTTP.sys is pretty nice and fast too. I’ve never had reliability or crashing issues with IIS: if your worker-process goes down it means your application code has a crashing bug in it, not IIS.
Yeah, nginx is nice - but is also a relatively recent tool (since 2004, I didn’t start seeing people prefer it for projects until after NodeJS gave them a reason to use it - so around 10 years ago). While nginx supports Windows, there’s a big fat caution saying it’s performance is sub-par still: https://nginx.org/en/docs/windows.html
So if you’re on Windows - because you’re a (non-Linux) .NET shop, or want/need to run on on-prem Windows Server boxes (especially SMB scenarios) it just makes sense to use IIS: it’s already there and certainly is not an underperforming, insecure, or otherwise “bad” web-server.
In the company Slack, I said something like "Serious question; is there something that IIS does better than something like Nginx or any other open source server?"
One of the most senior engineers responded back with "crashing".