Slack

Slack is a messaging app for workplaces. Stewart Butterfield and colleagues built it from an internal tool used while developing a game called Glitch. The company was then called Tiny Speck, and Slack opened to the public in 2013.

Conversations are organized in channels, usually by topic or project. Teams can also send direct messages, share files and start audio calls called huddles. Slack connects to thousands of other tools, so notifications from code repositories, calendars and help desks can arrive in a channel.

Salesforce bought Slack in 2021. It operates as a product inside Salesforce but keeps its own brand. The service is used by companies of all sizes and by communities and schools. Slack adds AI features for summaries and search across a workspace's messages. Slack was among the fastest growing business apps of its day. It later faced competition from Microsoft Teams, which is bundled with Microsoft 365. Slack Connect allows two companies to work together in a shared channel, which suits agencies and their clients.