An apparatus for a real-time collaboration in calendar is described herein. The apparatus includes a state change module to receive a change notification at a second calendar client rendering a shared calendar. The apparatus also includes an identification module to retrieve an identification (ID) of calendar content, a change in a user interface state, and an extent of a calendar view from a first data structure. Finally, the apparatus includes a replica module of the second client to retrieve calendar content from a second data structure using the ID as an index value.