Is it compulsory to buy webhosting along with a domain name?

Bluntly said yes, you need a webhosting service for any domain but:

- you may go with cloudflare, if you actually have a webbuilder based website (like one from brizy, http://website.com etc)

I suggest spending an amount on webhosting, that way your webhost has some accountability on your data and you get more features and benefits than cloudflare.