Simple Contacts - Contact lens prescriptions from home
Kontact - Kontact is the integrated Personal Information Manager of KDE.
Messages by Gather Media - Messages is an app by Gather Media that allows users to get notification alerts about new messages on the basis of priority level.
Nextcloud Contacts - The Nextcloud contacts app is a user interface for Nextcloud's CardDAV server.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts
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.