Slack

Slack is a cloud-based team communication platform founded in 2013 by Stewart Butterfield (Flickr co-founder), released from a failed gaming company (Glitch) and now the dominant business messaging tool with 42 million daily active users. Slack's channel-based model organizes conversations by topic, project, or team rather than email threads — channels persist, are searchable, and allow team members to join/leave as context demands. Slack's integrations ecosystem (2,600+ apps) connects with GitHub, Jira, PagerDuty, Datadog, Salesforce, Google Drive, Zoom, and virtually every business tool — turning Slack into the notification hub for engineering organizations. Slack's Workflow Builder automates repetitive processes without code: new employee onboarding flows, incident response runbooks, and standup collection all run natively in Slack. Slack Huddles (2021) provide lightweight audio/video calls directly in channels, competing with Teams calls and Zoom for quick synchronous communication. Slack Connect extends channels to external partners and customers, enabling cross-company collaboration in shared channels. Slack's search and file sharing make it a lightweight knowledge repository. Slack was acquired by Salesforce for $27.7B in 2021 — Salesforce integration deepened via Slack Sales Elevate and Salesforce channels. Slack's enterprise edition adds data loss prevention, e-discovery, and compliance export. The main competitor threat is Microsoft Teams, which reached 300 million DAU with Office 365 bundling. Slack holds its premium position with developers and tech companies through superior UX and the integrations ecosystem but faces pressure from Teams' zero-marginal-cost bundling strategy.