The bottom of the article links to the history (individual features) of other IM programs from that era as well like ICQ and Yahoo Messenger.
Both. Trillian was not Mac only (I made a mistake from memory), Pidgin was multi platform but started on Linux. Pidgin had every protocol. I still keep my .purple config folder and logs after over a decade. Not like I’ll ever read the logs again, though.
Edit: Guys, relax. I made a mistake recounting from memory. I didn’t run Windows back then. I assumed that because of the native Aqua interface, there wasn’t a Windows port.
Trillian was not Mac only. I’ve never owned a Mac and used Trillian almost exclusively from 2002 until roughly 2009?? I can’t remember when the transition from IM to texting happened for me, but it was around then. When I was running Linux at home I would use Gaim, which was developed by a friend of the main Trillian guy.