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.
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Nextcloud Contacts - The Nextcloud contacts app is a user interface for Nextcloud's CardDAV server.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.