I used asp.net in a project in an old company. The vs was licensed etc. Right now, I am planning to use mono since my new company is using linux based stuff and I heard that mono uses the .net framework etc. I just want to know if I need to purchase anything or is it ok to create a webapp using mono?
You can create a webapp using mono wihtout buying anything, of course. You only buy from Microsoft the license of Visual Studio, not the .Net compiler nor the Framework.