Slack

 Slack  is a closed-source team communication tool similar to IRC but with expanding support for various types of content such as emoji polls, inline images, and attachments.

Until 2018, Slack offered the ability to connect to their proprietary system using the open standards IRC and XMPP, but it was announced on March 6 2018 that this support would be phased out, starting immediately and completing on May 15, 2018.

IndieWeb Slack
We have an IndieWebCamp Slack team. It has channels for each of our IRC channels so there is still one "chat room" per subject area whether you use Slack or IRC.

Create an account on the IndieWeb Slack:
 * https://chat.indieweb.org/slack

Join the IndieWeb Slack rooms using your web browser:
 * https://indiewebcamp.slack.com/

What is Slackbot
Slackbot is the bot that appears in Slack.

Experience
People love Slack HQ. They make it clear to see who’s speaking with avatars and whitespace, offset the speaker from the text, make it clear what the person said, and de-emphasize the timestamp and room actions. They also support emoji. Caveat: I’ve never used it, I just know they’re doing something right because people are fanatical about it. — User:Chloeweil.com

POSSE to
It may be possible to POSSE posts to slack, e.g. even photo posts.

No known IndieWeb Examples of people POSSEing to Slack.

History
The makers of Slack previously made:
 *  Glitch  is a now-defunct game created by the founders of Slack.

This has nothing to do with current Glitch thing(s).

IRC Gateway
Slack operated an IRC gateway enabling connecting to a Slack instance from an IRC client. In March 2018 they announced it will be shut down in 2 months.

Note that this does not affect the IndieWeb IRC/Slack bridge, since that uses the Slack API directly to connect our IRC and Slack channels.