Recently, I faced the need for a synchronized calendar, i. e. a calendar synchronized between multiple devices (PC, smartphone, tablet) and maybe different persons (sharing a single calendar). Some of the big freemail providers like Google or Live/Outlook.com (Microsoft) offer online or web-based calendars. But those systems have limitations or issues such as residing in the U.S.A. (no protection for non-US citizen) or are tied to a certain application or non-standard protocol. So, there is need for a more generic solution.