Slack

Slack’s symbol is a rotated hashtag constructed from eight rounded pill shapes arranged in pairs. Each pair, oriented at 0, 90, 180, and 270 degrees, carries a distinct color: sky blue (#36C5F0), green (#2EB67D), amber yellow (#ECB22E), and rose red (#E01E5A). Where two pairs intersect, a mixed-color rounded square forms at the corner. The wordmark sits in Aubergine (#4A154B), a deep purple that provides a neutral typographic anchor for the multi-color symbol. The 2019 version, designed by Pentagram’s Michael Bierut, replaced an eleven-color predecessor that was difficult to reproduce consistently.

Logo history

Slack launched in 2013 with a symbol derived from the octothorpe, the hashtag character, because the hashtag had become the primary organizing structure of the platform’s channel system. The original mark used eleven distinct colors in a plaid-like arrangement, creating a symbol that was distinctive but notoriously difficult to reproduce: minor color shifts in printing or screen rendering could make it look wrong. Pentagram’s 2019 redesign solved this by reducing to four colors and creating a more geometrically consistent arrangement where each color appears exactly twice. The simplified symbol reproduced cleanly across every medium where Slack appeared, from Slack-branded Zoom backgrounds to office signage.

Design philosophy

The four-color system maps loosely to Slack’s core promise of converging different communication streams; the color pairs meeting at their intersections visualize information flowing together. Bierut’s team chose to round every corner of the pill shapes, departing from the original’s sharper geometry, which softened the industrial hashtag reference without losing its recognizability. The Aubergine wordmark is an unusual choice for a technology brand (purples are more common in consumer wellness or luxury branding), but Slack’s brand team has noted that it creates an immediate visual distinction from the blues and grays that dominate enterprise software.

Brand identity

Slack’s visual system extends the four accent colors throughout the product interface as category colors: channels, direct messages, apps, and notifications each receive consistent color coding drawn from the brand palette. The symbol appears on app icons, merchandise, conference materials, and the custom emoji library that Slack users have made into a significant sub-culture. The Salesforce acquisition in 2021 retained Slack’s visual identity without modification, allowing the brand to operate independently within the Salesforce portfolio.

Cultural impact

The 2019 rebrand became a widely cited case study in how to solve a reproduction problem without losing brand equity. Design publications covered Pentagram’s rationale in detail, and the before-and-after comparison (eleven colors reduced to four) became a reference point in discussions about brand system scalability. Slack’s influence on workplace communication culture created the phenomenon of “Slack etiquette,” making the logo a shorthand for the asynchronous messaging behavior that became standard in knowledge work, particularly after 2020.