At its core, Calgoo is a calendaring tool that allows you to sync calendars across platforms, including iCal, Google Calendar, Outlook, and 30 Boxes. While it started out as a very basic service about 2 years ago, Calgoo has developed into a mature calendar sharing solution with three separate products: Calgoo Calendar, an online calendar, Calgoo Connect, its calendar syncing application, and Calgoo Hub, an online calendar sharing service.

Judging from the change in business models, however, it would seem that Calgoo couldn't attract enough paying users. It's interesting that Calgoo couldn't make its 'freemium' model of free basic services and paid advanced feature work.

According to Calgoo, it is making its products available for free in order to "move to in-calendar advertising business models." While Calgoo hasn't outlined what these in-calendar ads would look like, this move is also consistent with the overall trend on the web towards advertising financed products.

As Svetlana Gladkova also points out in this context, users have simply become so accustomed to not paying for anything on the web that even charging for premium features is becoming very difficult for some companies. Calgoo must have surely felt the same pressure. In the short run, this is probably to the users' advantage.