Slack is a cloud-based proprietary instant messaging platform developed by Slack Technologies and one of the most popular collaboration software of the moment.
Slack provides mobile apps for iOS and Android in addition to their Web browser client and desktop clients for macOS, Windows, and Linux (beta). Slack is also available for the Apple Watch, allowing users to send direct messages, see mentions, and make simple replies.
It was featured on the home screen of the Apple Watch in a 2015 promotional video. Slack has been made to run on a Super Nintendo Entertainment System via Satellaview.