Psi is described as 'An instant messaging application for Windows, Linux, and Mac OS X that connects to the free, open XMPP network' and is a popular app in the Social & Communications category. There are more than 50 alternatives to Psi for a variety of platforms, including Mac, Windows, Linux, Android and BSD. The best alternative is Jitsi, which is both free and Open Source. Other great apps like Psi are Pidgin (Free, Open Source), Conversations (Free, Open Source), Facebook Messenger (Free) and Utopia (Free).
Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, GTalk/Hangouts extensions, as well as OTR, ZRTP, etc.
Pidgin is an easy to use, multi-protocol chat client client used by millions. Connect to AIM, MSN, Yahoo, XMPP, and more chat networks all at once. It has built-in support for NSS, offering client-to-server message encryption for protocols that support it.
Conversations is a privacy focused, open source XMPP Texting [Jabber] client for Android 4.0+ smart phones with wife-approved easy encryption [OTR, OMEMO, or GPG]. [Note] **You can download the compiled apk for free from F-Droid**: ...
Utopia P2P Ecosystem. Utopia is a feature-rich platform that is specifically designed to protect privacy of communication, confidentiality, and security of personal data. Utopia is a decentralized network, with no central server involved in data transmission or storage.
Bitmessage is a P2P communications protocol used to send encrypted messages to another person or to many subscribers. It is decentralized and trustless, meaning that you need-not inherently trust any entities like root certificate authorities.
An alternative Telegram client based on TDLib, with higher speed, slicker animations and experimental features. The goal of Telegram X is to reinvent Telegram and explore new frontiers in speed, ease of use, quality of animations and all other aspects.