Slack's 2019 identity, crafted by Pentagram under Michael Bierut, distilled a chaotic rainbow into a disciplined four-color lozenge mark anchored by aubergine purple. The result is a brand that reads as both approachable and enterprise-ready — a serious collaboration tool that never feels cold.

The design system leans on rounded geometry, generous whitespace, and restrained use of its quadrant accents (yellow, green, blue, pink) to create interfaces that feel conversational rather than corporate.