Free open source end-to-end encrypted peer-to-peer calling and messaging app. It supports video calls, audio, messaging and has a Skype-style interface. It has apps for all major platforms including Android, iPhone/iPad, Linux, Mac and Windows.

Fediverse address:

The XMPP Standards Foundation

Develops and maintains the XMPP standard for instant messaging and voice and video calls. It’s a free open federated standard, so anyone can set up their own server or write their own app. (XMPP used to be known as Jabber.)

Fediverse address:


A free open source video conferencing site which aims to provide a privacy-friendly alternative to proprietary services. Calls are made through the web browser using the BigBlueButton platform.

Fediverse address (in German and English):