Xabber
Open source Jabber (XMPP) client with multi-account support, clean and simple interface.
21 Alternatives To Xabber
Adium
Adium is a free instant messaging application for Mac OS X that can connect to AIM, MSN, Jabber, Yahoo, and more.
BitMail
Secure decentral P2P Email
ChatSecure
ChatSecure is a free and open source messaging app that features OTR encryption over XMPP.
Conversations
XMPP client designed with ease of use and security in mind
Disa
Disa is your new messaging hub.
Facebook Messenger
Facebook Messenger is a faster way to message.
Gajim
Full featured and easy to use Jabber client
Google Duo
Google’s answer to Facetime, high-quality video calling on iOS and Android.
Jitsi
Open-source video calling and chat platform.
Pidgin
Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once.
Signal
Fast, simple & secure messaging. Privacy that fits in your pocket.
Telegram
Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Threema
A secure, end-to-end encrypted Swiss instant messenger with a focus on privacy.
Tox
Send messages, files, create groups and make Tox to Tox audio and video calls. Securely.
Trillian
Trillian is a decentralized and federated instant messaging platform that lets your whole company send private and group messages, keep tabs on what co-workers are doing, share files, and much more.
Viber
Free and secure calls and messages to anyone, anywhere. Keep your conversations going no matter where you are.
WhatsApp
WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Wire
Private & Secure Messenger
YakYak
Desktop client for Google Hangouts
Zulip
Powerful open source group chat