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.
WPAmelia - Award-winning WP booking plugin that manages services, appointments, customers, events, analyze business performance, and accept payments online.
Doodle - Make meetings happen. With Doodle, scheduling becomes quick and easy.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Appoint.ly - Appoint.ly helps to schedule meetings quickly and easily through the integration with calendars online.
Koalendar - Free Online Appointment Scheduling Software