Recs.
Updated
Discord is a free voice and text communication platform targeted primarily at the gaming market. It aims to match the ease of use of existing chat clients like Skype and mix it with the power of servers with multiple rooms and role permissions offered by voice clients like Teamspeak.
SpecsUpdate
Pros
Pro Syntax highlighting and Markdown support
The support is limited but still exists. It's a killer feature for dev teams.
Pro Friendly payment policy
Free account have no tangible restrictions.
Premium account is just a way to say "thank you" to developers. And it work for all servers of discord (not as in slack). And it can be purchased by one who wants. In contrast to Slask, where all active members of the server should be "premium".
Pro Does not allow NSFW related things to be posted unless in a NSFW channel
Cons
Con Developer's previous company was sued for privacy violations, among other things
See:
http://classactionlawsuitsinthenews.com/class-action-lawsuit-complaints/openfeint-green-international-privacy-class-action-lawsuit-complaint/
https://www.ftc.gov/enforcement/cases-proceedings/closing-letters/openfeint-inc
Discord's privacy policy also states that while they might not sell your data, a company they get sold to will quite possibly attain said data and thus may be in "more" shady hands.
Con Not a generic "team chat" tool
All the UI and the features are aimed specifically at communicating with your gaming team/clan.
Recommendations
Comments
Flagged Pros + Cons
Pro Cross-platform
Discord has native desktop apps for Windows, OSX and Linux, and mobile (Android, iOS) platforms and it's also accessible from the web.
Con No linux support
No native linux support
Discord DOES actually currently support linux
Con No chat search (updated, search has now been added)
Discord has been updated and now DOES have a chat search in the top right corner
Con Prioprietary (non-free/libre)
Discord only recently added in a pro feature, and it is only for small things like GIF profile images. Staying free in no way reduces functionality and does NOT have ads.
Con Often corrupted downloads, updates or files
Having to clean up cache all the time when it gets stuck, messes up due to a buggy release or even rips apart dll's
Out of Date Pros + Cons
Con Servers only in select regions
Servers are currently only available in the US, Europe, and Singapore. This can mean poor latency for users located elsewhere.