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.

Sidekick by Hubspot - Customer insight integrated with your email tools.

Google Calendar - Spend less time managing your day & more time enjoying it

Sansan - Sansan provides a internal contact sharing service for companies.

Apple Contacts App - Access and edit your contacts from personal, business, and other accounts with the Contacts app.

HiHello - Exchange contacts, seamlessly.