Slack Technologies Inc.

Slack Technologies, Inc. is an American software company founded in 2009 in Vancouver, British Columbia, Canada, by Stewart Butterfield and a team largely composed of former Ludicorp members, the creators of Flickr.

Initially, Slack was developed as an internal communication tool for Butterfield’s company, Tiny Speck, during the creation of the online game Glitch. The name “Slack” is an acronym for “Searchable Log of All Conversation and Knowledge.”

Headquartered in San Francisco, California, Slack operates offices in major cities including Dublin, Vancouver, New York City, Toronto, Denver, London, Tokyo, Pune, Paris, and Melbourne.

In February 2015, Slack experienced a data breach, compromising user information such as email addresses, usernames, hashed passwords, phone numbers, and Skype IDs. In response, the company introduced two-factor authentication to bolster account security.

Slack went public on the New York Stock Exchange in June 2019 via a direct stock listing. In December 2020, Salesforce announced its acquisition of Slack for $27.7 billion.

On January 4, 2021, Slack suffered a major outage lasting several hours. Users encountered difficulties logging in, sending messages, making calls, and using integrations. While core functions were restored later in the day, some services, including push notifications and calendar integrations, remained disrupted.

Slack provides features similar to IRC, including persistent chat channels categorized by topic, private groups, and direct messaging. All content—files, conversations, and user information—is searchable. Users can also react to messages using emoji.

Slack’s free plan limits users to viewing and searching only the 10,000 most recent messages.

The platform has faced criticism for exclusively storing user data on cloud servers controlled by the company, causing concerns about connectivity, access to archived messages, and user capacity limitations for large teams.

Additionally, Slack’s 2018 privacy policy update drew criticism for allowing workspace administrators access to all public and private chat messages without requiring user consent or notification when data is accessed.