Apache UserGrid - Usergrid is an open-source BaaS enabling developers to rapidly build web and/or mobile applications.
Calendly - Say goodbye to phone and email tag for finding the perfect meeting time with Calendly. It's 100% free, super easy to use and you'll love our customer service.
Baqend Platform - Baqend is a Backend-as-a-Service for web and mobile apps.
Acuity Scheduling - Automate your client bookings, cancellations, reminders & payments using the worlds friendliest online scheduling software.
ApiOmat - ApiOmat is a Mobile Backend as a Service enabling organizations to integrate their enterprise IT systems with mobile devices and wearables.
Reservio - Reservio is a simple online booking and appointment scheduling application.