Hi Friend,
Absolutely Yes, .Net is free, opensource and now truly cross platform with the .Net Core framework launched in 2016. This means you can write .net code for any platform and not just windows. .Net and .Net Core is the #1 framework of choice when it comes to making Web Apis. Reason being the really cool and snazzy Middle-ware which is available to the developers out of box. This saves a lot of time and increases the productivity tremendously.