Add Zusam

README.md

@@ -476,6 +476,7 @@ _[SIP](https://en.wikipedia.org/wiki/Session_Initiation_Protocol)/[IPBX](https:/
 - [Thredded](https://thredded.org) - Forums, feature-rich and simple. ([Demo](https://thredded.org/thredded), [Source Code](https://github.com/thredded/thredded)) `MIT` `Ruby`
 - [twister](http://twister.net.co/) - Fully decentralized P2P microblogging platform leveraging the free software implementations of Bitcoin and BitTorrent protocols. ([Source Code](https://github.com/miguelfreitas/twister-core)) `MIT` `C++`
 - [Vanilla Forums](https://vanillaforums.org/) - Simple and flexible forum software. ([Source Code](https://github.com/vanilla/vanilla)) `GPL-2.0` `PHP`
+- [Zusam](https://zusam.org) - Free and open-source way to self-host private forums for groups of friends or family. ([Demo](https://demo.zusam.org), [Source Code](https://github.com/zusam/zusam), `AGPL-3.0` `PHP`
 
 ### XMPP