SilentSuite - Secure Data Sync

End-to-end encrypted sync for calendar, contacts, and tasks

Nextcloud Dev

Synchronization client

Bondwidth

Private, offline phone & contacts app that helps you keep up your bonds

Libre Contacts Backup

Offline contact backups with optional encryption

solyto

Free, private, all-in-one personal organizer. Self-hostable.

Nextcloud

Synchronization client

pcontacts

Sync Proton Mail contacts into the Android system address book.

Solid Share

Files, contacts and passes on your own Solid pod, shared on your terms

OpenContacts

A different database for contacts to keep them private only to you.

Fossify Contacts

Manage your contacts privately and efficiently with vCard support

ChatLaunch for WhatsApp

Start WhatsApp chats without adding numbers to contacts.

WhatsApp Contact Adder

Add WhatsApp contacts without giving WhatsApp access to your contacts!

Friend Alert

Nurture distant friendships with timely reminders

Contacts Import

Import your CSV contacts from a desktop client without any cloud syncing.

Identiconizer!

Identicons for your contacts