Alternativa Bookisu za Google Calendar z licenco odprtokodnega vira

• Google Calendar
  Vse platforme Windows Mac Linux Chrome OS Android iPhone Windows Phone iPad Android Tablet Web Self-Hosted Software as a Service (SaaS) PHP jQuery Windows Mobile Slack Microsoft Office Outlook Chrome Google Calendar Sunbird Google Apps Microsoft Exchange Server Apple Calendar
• Open Source licenca
  Vsako dovoljenje Brezplačna licenca Open Source licenca Trgovsko dovoljenje