Community Builder. Community Builder (CB) is the most popular and flexible social community networking solution for all versions of Joomla!
(3.2, 3.x and 2.5 with ACL support). For over 9 years now the 500,000 and growing Joomlapolis members have made CB the most widely used (over 2,500,000 public installs per Google) social networking solution. It’s FREE and has always been GPL. Social websites go far beyond Facebook look-alikes and CB has literally hundreds of built-in features and extra (free or commercial) add-ons from CB Team and other parties that will help you realize your very own - tailored to your specific needs - website. CB also has a powerful built-in framework (CB API doc. is available on Joomlapolis) so it can be extended and enhanced. Community Builder - Joomla Social Networking.
JomSocial. I've been a paying member of JomSocial for years.
Over that time prices have doubled, the support forum disappeared, and reappeared, and noticeable upgrades were implemented in their software. Some of these were frustrating changes; some were nice to see. But, I'll tell you one thing - I'm still a paying member - because they clearly are working hard, trying their best to improve the product and support, and I know that they will always be around (and that means my community will be as well). Price: I was a member back when plans were 1 year long. Now, the plans are the same price, but only good for 6 months. Open Source Community Software.