free uploading web site

There is nothing as free lunch my friend. ;)
If it is for learning purpose, you can use the new/cool Windows Azure. They are offering 90 days free trial.

https://www.windowsazure.com/en-us/pricing/free-trial/[^]

Else if it is real/business application, I would rather buy a hosting account and deploy it there.

It's not called "free uploading", this is "free Web hosting". Such things do exist. Mostly they are commercial services, but with free plan, mostly intended to attract try-before-you by users. Actually, any reasonable user is like that, all other are… I don't know who, probably just loosers. :-) And such free plan can be unlimited. If you can find a free plan with such setting, it's probably the best. Other options could be ad-based (no, this is not good for you) or very low quality.

Now, the problem is: it's relatively easy to find such service based on Apache and offering mostly PHP, and much, much harder to find something with ASP.NET. I, for example, would like to have Apache with ASP.NET based on mod_mono, and this is even harder to find. Anyway, do your own search and your own trial.

—SA