Miranda NG is a multi-protocol instant messaging client supporting most common protocols by default including Facebook, GG, ICQ, IRC, Jabber and MSN. However, additional protocols (including Discord, Skype, Tox, Twitter etc.), plugins and languages are available via “Main menu > Show full plugin list” (see online list).
As the program is a code fork of Miranda IM, an FAQ about the differences is available.
Alternatively, Miranda NG Portable is also available.