Plan - Plan is a better way to organize.
Cronofy - Unified Calendar API for developers
Kin Calendar - The simple and connected calendar
Calendarix - Calendarix is a powerful and easy to use web-based calendar that runs on PHP and MySQL.
Kin - Kin is money for the digital world. It is used to generate value through a shared, decentralized cryptocurrency in a digital ecosystem of apps and their users.
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.