Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Rainlendar - Rainlendar - Customizable desktop calendar
Google Calendar - Spend less time managing your day & more time enjoying it
Apple Contacts App - Access and edit your contacts from personal, business, and other accounts with the Contacts app.
Gmail - Gmail is available across all your devices Android, iOS, and desktop devices. Sort, collaborate or call a friend without leaving your inbox.