What is Keybase? Simply put, its a collaboration and verification network. Taken verbatim from their website:

Communities, families, friends, schools, and companies. Keybase is for everyone, and it’s growing fast. Unlike Slack, it is free. And without ads.

If your data is in the cloud, it should be encrypted. If you’re putting people together, give Keybase a try.

keybase.io

As mentioned above, Keybase is a much more secure and forward looking & most importantly free alternative to slack, with encrypted text & audio chat, file sharing, file encryption, PGP verification and a built in stellar wallet. It also allows you to form work groups or teams and sub-teams.

Its back-end uses a cryptography called sigchain which uses user interaction to secure the chain of trust between interacting users. each verifying each others actions as they interact.

.Sign up now to be entered into an airdrop of stellar tokens, every month for up to 2 years! In the last airdrop i received 688 XLM equivalent to $49.70 at the time of writing.