Empathy - Apps/Empathy - GNOME Wiki!
Fluid - Turn Your Favorite Web Apps into Real Mac Apps.
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.
WebCatalog - Run your favorite web apps natively
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.
Unite for macOS - Turn websites into native apps on your Mac.