Dudle - Dudle is an online scheduling application, which is free and open source.
Prekindle - Prekindle is a simple yet powerful event management, ticketing, and marketing platform that helps businesses to sell tickets to the event online and spread the word.
Pulse 24/7 - Booking & scheduling mobile app for service providers
Tix - Tix is a state-of-the-art, cloud-based ticketing system that features fully integrated access controls, event management controls, multi-channel distribution capabilities, and a robust reporting suite.
MakePlans - Online appointment booking - MakePlans
EventTitans - Top rated event management software