FareHarbor - Reservation software for activity and tourism businesses. Low credit card processing rates, mobile friendly. Built for you.
Baïkal - Cal and CardDAV server
Peek Pro - Peek Pro is a fastest growing appointment scheduling software specially designed for tours and activity operators to help increase their booking reaching out to large numbers of potential customers, mostly tourists.
Radicale - The Radicale Project is a complete CalDAV (calendar) and CardDAV (contact) server solution.
Resmark - Resmark provides online booking software and marketing automation for activity, lodging and rentals.
DAViCal - DAViCal is a server for calendar sharing.