Meetingbird for Gmail - View your calendar and schedule meetings right from Gmail
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.
Kin Calendar - The simple and connected calendar
Polymail Calendar - Schedule meetings instantly over email
Vyte for iOS - Schedule meetings on the go
Google Calendar - Spend less time managing your day & more time enjoying it