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.

Franz - Franz is your messaging app for WhatsApp, Facebook Messenger, Slack, Gmail, Telegram and many many more.

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.

Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!

Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.

Google Duo - Google's answer to Facetime, high-quality video calling on iOS and Android.