this XEP is supported by the most popular XMPP servers (prosody, ejabberd) but it is still quite difficult to get a good XMPP client on all platforms that can s

this XEP is supported by the most popular XMPP servers (prosody, ejabberd) but it is still quite difficult to get a good XMPP client on all platforms that can support this. this is especially important for mobile clients on iOS or Android or web clients. I don't see another way to have OSS multi-client chats with XMPP similar to hangouts/Facebook/WhatsApp.