A no deposit bonus may often become available right after completing the registration, as in most cases the only requirement for it, is sign up and then verification of your newly created account. Each website has its own rewards program as well as it does software platform, powered by one or more providers that made those games accessible.
No deposit casinos are nothing else than online casinos that feature no deposit bonuses and selected games to which these bonuses apply.
When it comes to playing online games for free, then the best way to do that would probably be by joining any no deposit casino site.