Chipmunk Forum is a small yet flexible and fully featured forum system. It has unlimited categories and forums, staff only forums, read only forums, and 4 levels of permissions. Permission levels include moderators, supermoderators, admin, and head admin. Chipmunk forum includes multiple smilies, word filters, BBcode, Ip banning, e-mail ban from registration and much more. You may modify the code and release any hacks or mods of it as long as the copyright notice to chipmunk scripts stays intact and the mods/hacks/skins you release are free.
Invision Power Board is written in PHP scripting language combined with the MySQL database system. Features include: Fast and efficient programming and database usage; Customize the look of ever page using standard HTML in the skinning system; Powerful and easy to use administration area and tools to control your board and your members; No limits on storage of posts or topics; COPPA support to comply with the new laws; Professional support services and enhancements; User tools; Calendar; Back up tools; Post uploads; Power search & help center.
Orca Interactive Forum Script is based on AJAX technology, and can be fully integrated into any community software. Orca has the following outstanding features: Self Ruling forum ( administrator needn't waste time to moderate or administer the forum, since a community members can do it themselves), Sticky Topics (it's easy to make announcements for your community members), Live post tracker-"Forum Spy", RSS feeds support, Live Tracker (works in real time), TinyMCE, Reply with Quote (the ability leave a comment or post reply inside the post). Orca is reliably tested on sites and already proved to support over 20000 registered members smoothly without server overload. Another great feature is that Orca is spread in terms of a General Public License (GPL). Orca is the best forum for your community site.
A light-weight flexible PHP forum package that uses object-oriented programming and the MySQL database. It's purpose is to act as a fast (and free) alternative to other forum packages which are noticably slow or have everything but the kitchen sink. Fast and secure with execution times averaging 0.2 seconds. Automated installer script for easy set up. Unlimited categories and forums, all with configurable permissions. Full Administrator Control Panel for managing the forum and its users. Full support for output "skinning".
phpBB is a high powered, fully scalable, and highly customisable open-source bulletin board package. phpBB has a user-friendly interface, simple and straightforward administration panel, and helpful FAQ. Based on the powerful PHP server language and your choice of MySQL, MS-SQL, PostgreSQL or Access/ODBC database servers, phpBB is the ideal free community solution for all web sites. Features include: Unlimited forums and posts; Multiple language interface; Private or public forums; Powerful search utility; Private messaging system; Templates.