Salesforce agreed to acquire Slack in 2020 for $27.7 billion in an acquisition combining cash and stock.
Slack began as an internal communication tool created during development of the online game Glitch. Stewart Butterfield and his team released Slack publicly in 2013, and it grew into a workplace platform organized around channels, direct messages, file sharing, and integrations with other business software.
Salesforce announced the agreement in December 2020, during a period when remote and hybrid work had sharply increased demand for digital collaboration tools. The transaction closed in July 2021 after regulatory review. Slack continued as a separate product and brand inside Salesforce, while Salesforce positioned it as an interface for collaboration across its customer-relationship-management products. This was not the same as Salesforce acquiring a traditional email provider: Slack’s core identity was real-time team messaging and an extensible app ecosystem.