SilentSuite - Secure Data Sync

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

Nextcloud Dev

同步客户端

Bondwidth

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

Libre Contacts Backup

离线联系人备份，可选加密

solyto

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

Nextcloud

同步客户端

pcontacts

将 Proton Mail 联系人同步到 Android 系统通讯录。

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

安全高效地管理联系人，带有 vCard 支持

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