Eion Robb has done an incredible amount of work in this space. His GitHub page[1] has tons of plugins, and I particularly appreciate the work he has done on the Matrix plugin to make it available to Windows users.
Lest you think this is less than cool because you don't use Pidgin, bitlbee[2] is a great tool to get slack (and others!) into your IRC client. I haven't run it myself, but I know that it heavily relies on purple[3] for its magic. I can tell it gets a lot of use, perusing the issues on the slack purple plugin[4] for example.
The protocol is far from being os-specific, but it does call for a lot of crypto facilities calls, which if you're not careful you might end up making os-specific.
Less OS specific and more "compilable", he took a plug in that was written in C and made sure it was cross-platform enough and compiled it on Windows for us.
Lest you think this is less than cool because you don't use Pidgin, bitlbee[2] is a great tool to get slack (and others!) into your IRC client. I haven't run it myself, but I know that it heavily relies on purple[3] for its magic. I can tell it gets a lot of use, perusing the issues on the slack purple plugin[4] for example.
1: https://github.com/EionRobb?tab=repositories
2: https://www.bitlbee.org/main.php/news.r.html
3: https://wiki.bitlbee.org/
4: https://github.com/dylex/slack-libpurple/issues?q=is%3Aissue...