Can I host my .NET app on Render? Yes! You definitely can.
Render has a limited set of native runtimes that you can use to simply connect your repo and deploy. But if you have a dockerfile, you get control of the runtime to use any language/OS you want. Render builds your image and deploys it for you, including .NET images!
I’m not a .NET developer, but using an OSS repo from Microsoft with a sample ASP.NET app with a dockerfile, it’s very easy to deploy it using the
Docker runtime configuration. To note, the dockerfile builds the application inside of the docker container and runs the binaries with the .NET runtime.
Having the build step in the dockerfile is standard for render’s docker runtime, since we can’t guarentee anything about the build machine render provides us like we can for the native runtimes. But, your other option is to build the docker image yourself, and in render, create an image-backed service to deploy directly from a container registry.