Phalcon official Forum
CodeIgniter Forum Library is the first version of a simple library for framework CodeIgniter
Simple PHP Forum Application
A high performance open-source forum software written in PHP. Discussions Tags based with Quora/StackOverflow style.
A free, open source, PHP-based simple discussion forum. It favours removing barriers to conversation rather than massaging egos. Download Here: https://github.com/Kroc/NoNonsenseForum/archive/master.zip
ElkArte Forum. A free, open source, PHP-based discussion forum.
Quick Community is a Fast Forum programmed in PHP and using SQL with PDO
Vanilla is a powerfully simple discussion forum you can easily customize to make as unique as your community.
This is a simple E-commerce Discussion forum designed completely in PHP. This forum is Easy to Use and the UI is highly impresive. User Authentification feature yet to come.