Slack

Slack is a team messaging platform organized around channels, threads and direct messages, with audio and video huddles, file sharing and a Workflow Builder for simple no-code automations. It is the default chat tool for a large share of technology companies and is used across most industries, from small startups to enterprises on Enterprise Grid. Slack Connect lets separate companies share channels, which agencies and vendors use to work with clients.

What stands out is the app ecosystem: thousands of integrations, including first-party apps from Google, Microsoft, Zoom, Atlassian, GitHub and Salesforce, which owns Slack. Search, notification controls and custom emoji are mature, and the desktop and mobile apps behave consistently. Since mid-2025 AI features such as thread summaries and search answers have been bundled into paid plans, with the fuller set on Business+ and above.

The Free plan shows only the last 90 days of messages, caps integrations at 10 and limits huddles to one-to-one calls, which suits a small group but pushes active teams to upgrade. Pro is $8.75 per user per month ($7.25 billed annually); Business+ adds SAML SSO and full data exports at approximately $15 per user per month billed annually after a 2025 price rise. Costs add up quickly at scale, and channel sprawl and notification overload are common complaints.