A compilation of the nine most important discussion forum software:
bbPress, , Discourse, FluxBB, miniBB, MyBB, Phorum, phpBB, SimpleMachinesForum (SMF) and Vanilla.
bbPress
Discussion forums, for your WordPress.org powered site. bbPress is forum software from the creators of WordPress. Quickly setup a place for asyncronous discussion, subscriptions, and more!
Website:
https://bbpress.org/
Discourse
Discourse is the 100% open source discussion platform built for the next decade of the Internet. Use it as a mailing list, discussion forum, long-form chat room, and more!
Website:
https://www.discourse.org/
FluxxBB
FluxBB is an open-source forum application released under the GNU General Public Licence. Supports PHP5 & PHP7 and it is free to download and use and will remain so. FluxBB was conceived and designed to be fast and light with less of the «not so essential» features that some of the other forums have whilst not sacrificing essential functionality or usability.
Website:
https://fluxbb.org/
miniBB
Want to build a simple and easy, but many features powered forum of your own? Download miniBB – first little PHP bulletin board script on the planet. Free!
Website:
https://www.minibb.com/
MyBB
MyBB’s built-in template and theme editor gives you complete control over your forum’s design. Developed and refined to put you in full control of your forum. Infinite possibilities arise from every conversation on your forum. Features to keep your users engaged and active. Participate in private conversations with several registered users at a time.
Website:
https://mybb.com/
phpBB
Millions of people use phpBB on a daily basis, making it the most widely used open source bulletin board system in the world. Whether you want to stay in touch with a small group of friends or are looking to set up a large multi-category board for a corporate website, phpBB has the features you need built-in.
Website:
https://www.phpbb.com/
Phorum
Phorum is open source forum software with a penchant for speed. Phorum’s very flexible hook and module system can satisfy every web master’s needs.
Website:
https://www.phorum.org/
SimpleMachinesForum (SMF)
Simple Machines Forum — SMF in short — is a free, professional grade software package that allows you to set up your own online community within minutes.
SMF is written in the popular language PHP and uses a MySQL database.
Website:
https://simplemachines.org/
Vanilla
Vanilla Provides a Modern Community Platform. More than ever, your customers want a voice within a community of others who all share a common interest and purpose.
With so many sites competing for attention, a successful community must be engaging and reward member participation. Vanilla provides a modern customer community platform to organizations who want to improve customer service, increase advocacy, and strengthen brand loyalty.
Website
https://vanillaforums.com/