The best free alternative to XenForo is Flarum, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to XenForo and many of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to XenForo are phpBB (Free, Open Source), Simple Machines Forum (Free, Open Source), MyBB (Free, Open Source) and NodeBB (Freemium, Open Source).
Flarum is free, open-source forum software with a focus on simplicity. You can use Flarum to easily set up a discussion forum for your website. Flarum is developed openly on GitHub. It is the combined successor of esoTalk and FluxBB. It aims to be:
Since its creation in 2000, phpBB™ has become the most widely used Open Source forum solution. Like its predecessors, phpBB™ 3.2 “Rhea” has an easy to use administration panel and a user friendly installation process, which allows you to have a forum set up in minutes.
bbPress is forum software with a twist from the creators of WordPress. Its focused on web standards, ease of use, ease of integration, and speed. bbPress will try to keep things as small and light as possible while still allowing great add-on feature possibilities.