NodeBB is described as 'is next generation forum software. It's powerful, mobile-ready and easy to use'. There are more than 25 alternatives to NodeBB for a variety of platforms, including Self-Hosted solutions, the Web, Linux, Windows and Mac. The best alternative is Discourse. It's not free, so if you're looking for a free alternative, you could try Flarum or phpBB. Other great apps like NodeBB are Simple Machines Forum (Free, Open Source), MyBB (Free, Open Source), FluxBB (Free, Open Source) and Vanilla (Free Personal, Open Source).