Remind1 - Save nerves, time and money - send automated appointment reminder messages from the calendar you already use. Google Calendar & Outlook / Office 365 Integration.
Reminder - A better way to keep track of your reminders 📝
Remindy.me - Never forget anything!
Wonder for Slack - Remember the things your team forgets
Appointment Reminder - Automated SMS/Voice and Email Reminders.
Tiny Reminder - Collect content & files from busy clients