phpBB is free and open source forum software that is easy to use, powerful, and highly customisable. Our community offers extensive support to end users.
bbPress is forum software with a twist from the creators of WordPress. Easily setup discussion forums inside your WordPress.org powered site.
Vanilla provides hosted and open source community forum software that powers discussion forums on thousands sites. Built for flexibility and integration, Vanilla is the best, most powerful community solution in the world.
Simple Machine Forums (SMF)
Simple Machines offers free open source software such as SMF, the powerful and easy to use community forum written in PHP. Start interesting discussions on your website!
miniBB – Easy Forum Software for Easy People
miniBB is a standalone, open source program for building your own Internet forum, and it’s free to download. Comparing to the other forum software available on the market, miniBB just brings what it’s created for: an easy, lite, and speedy quick forum.
YaBB – Yet another Bulletin Board
YaBB is a leading FREE, Open Source community forum system (bulletin board, message board) written in Perl.
MyBB evolved from other bulletin boards into what it is today. It has encountered numerous staff changes and has often changed its appearance.
I’ve deceived to use SMF because its simplexity and very easy to manage. After a smooth installation, i ran into a problem that wordpress’s .haccess file take over smf because i put smf in a sub directory under wordpress.
I found a solution to let smf won’t be affected by wordpress’s .htaccess
Edit your wordpress’s .htaccess file, add this after RewriteBase /
RewriteCond %{REQUEST_URI} ^/forum/(.*)$
RewriteRule ^.*$ - [L]
This is what the .htaccess file should look like
# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} ^/forum/(.*)$
RewriteRule ^.*$ – [L]
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
# END WordPress