Comment by pmlnr

Cross platform, closed source, including Jingle (audio/video): http://astrachat.com/

Android (no audio/video): https://conversations.im/

Web: https://conversejs.org/

Web with extras: https://movim.eu/

Desktop (Mac): https://adium.im/

Desktop (Win): https://gajim.org/ (not sure about this)

Desktop (Linux): http://pidgin.im/ (needs extras: https://petermolnar.net/instant-messenger-hell/#extra-plugin... )