Version 6.0 is out now and available. You can auto install WHMCS 6.0.0 with one click via Softaculous. Here is the guide. You can also upgrade your existing installations to WHMCS 6.0.0 via Softaculous. Here is the guide.
Version 6 is packed with new features, watch the video below for a look at some of them in action.
Key Features in WHMCS V6 include :
Source : http://blog.whmcs.com