Dex is described as 'personal CRM designed to be much easier than a sales CRM. Dex reminds you to keep in touch with the people you care about. Easily visualize, understand, and manage all your relationships for free' and is an app in the Office & Productivity category. There are more than 10 alternatives to Dex for a variety of platforms, including iPhone, Online / Web-based, Android, Mac and iPad. The best alternative is EteSync. It's not free, so if you're looking for a free alternative, you could try Nextcloud Contacts or Monica. Other great apps like Dex are BusyContacts (Paid), Amicu (Freemium), Cisdem ContactsMate 5.6.0 (Freemium) and Hippo (Freemium).
The Nextcloud contacts app is a user interface for Nextcloud's CardDAV server. Easily sync contacts from various devices with your Nextcloud and edit them online. 🚀 Integration with other Nextcloud apps! Currently Mail and Calendar – more to come.
Cisdem ContactsMate can analyze, report, fix dozens of problems with OS X Contacts and export Mac Address Book to some formats for backup or sync. It also can make groups for contacts, batch fixes similar problematic contacts, manually set suffix.
Make notes, keep track of events and store to-dos for all your contacts. So next time you meet, a quick glance at the person's profile in Hippo is all you need to remember the details. Being attentive doesn’t have to be a challenge anymore.