A system is disclosed for users to manage calendars in mobile computing devices. The system retrieves calendar entries from multiple calendars of distinct calendar platforms, extracts event information from the retrieved calendar entries, and aggregates extracted event information. The system can simultaneously display calendar entries extracted from multiple calendars of distinct platforms. The system provides various features for users to operate the calendars, such as (1) hiding calendar entries from some calendars and visually distinguishing the time scheduled for the hidden entries from free time; (2) compressing the display of extended free time periods; and enabling users to (3) navigate time as a scrolling list not subject to the limitations of arbitrary calendar units (e.g., month, week).