Pidgin is a free and open-source chat client which supports AIM, Google Talk, ICQ, XMPP protocols.

Signal is the most scalable encryption tool.

Linphone is a free voice over IP (VoIP) service and SIP client.

LINE is a new communication app which allows you to make free voice calls and send free messages whenever and wherever you are.

Psi is a cross-platform powerful XMPP/Jabber client (Qt, C++) designed for the Jabber power users. Psi+ is a development branch of Psi IM XMPP/Jabber client.

Flock is a communication app for teams. Packed with tons of productivity features, Flock drives efficiency and boosts speed of execution.

QuteCom (WengoPhone) is a free-software SIP-compliant VoIP client.

Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption.

Facebook Messenger is the official Facebook app that lets you have text conversations with all of your friends on the popular social network.

Nextcloud is a suite of client-server software for creating file hosting services and using them. It is functionally very similar to the widely used Dropbox, …

WeChat is a social media with instant messaging, commerce and payment services application.

Qiscus provide everything you need to power up your app with chats.

SightCall remote support software enables live video streaming and remote access on mobile devices and desktops for customer service and tech support.