Signal is the most scalable encryption tool.

Kolab Now is a web-based email and groupware service, based completely on free and open-source software.

Conversations is an open source XMPP/Jabber client for the Android platform.

Otr.to is a browser based chat client.

Zulip is a chat and collaborative software.

Wire is a cross-platform, encrypted instant messaging client created by Wire Swiss. It is available for iOS, Android, Linux, Windows, macOS and Web browser cl…

Threema is an encrypted instant messaging application for iOS, Android and Windows Phone.

Sicher is a freeware instant messaging application for iOS, Android, and Windows Phone. Sicher allows users to exchange end-to-end encrypted text messages, me…

Mailfence is a web-based email service that offers OpenPGP based end-to-end encryption and digital signatures.