Dear communities, please try to refrain from using proprietary communication infrastructure whenever possible.
Since last year, the Matrix ecosystem evolved quite rapidly, and now features:
- Riot - a full fledged client for Web, iOS and Android which supports End-to-End-encryption
- a reasonable set of bridges to other networks like IRC, Slack or Rocket.Chat to only name a few, to increase interoperability of the diverse messaging services available to us nowadays.
Please also consult the Matrix FAQ for further information about the financing parties, the aims of the project and why it breaks with conventions to allow for new kinds of collaborations.
Below a few more links, including this one, for Reasons Not to Use Slack for Free Software Development or Why Slack is inappropriate for open source communications.