As an alternative to Slack, I highly suggest Discord, as it's completely free... and has a nice, dark interface, as opposed to Slack's blinding, unchangeable white. I use it for the majority of my gaming and RP-related chatter, already. It's also definitely not a resource hog - very low impact on the CPU. I leave it on all the time on my phone, and it doesn't devour the battery like Skype does. I've had absolutely no problems with notifications between desktop/phone/what-have-you. And it's also designed for use while gaming. Neat thing, that you can also set different nicknames for yourself for each server you're in, and you can have countless servers.
It's available for Windows, Mac, Android, and iOS. Also, they're working on making it available for Linux!
Also, Holly - It works for browsers other than Chrome. I've thus far tested it in Firefox and Edge, but if on the off-chance you use a different browser from the three already mentioned, I don't foresee issues popping up.
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