fruux - Free service that takes care of your contacts, calendars and more so you don't have to.
NinjaOne - NinjaOne (Formerly NinjaRMM) provides remote monitoring and management software that combines powerful functionality with a fast, modern UI. Easily remediate IT issues, automate common tasks, and support end-users with powerful IT management tools.
FullContact - Put the power of full contact information into your web or mobile apps.
Atera - The only IT management platform powered by Action AI™
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.
Microsoft Operations Management Suite - Microsoft Operations Management Suite enables user to gain visibility and control across the hybrid cloud with simplified operations management and security