Overview

Slack is a workplace collaboration software brand headquartered in San Francisco and owned by Salesforce. Its product organizes business communication into persistent channels, direct messages, searchable conversation history, files, integrations, and automated workflows. The service is positioned as an operating layer for teams rather than simply as an instant-messaging application: employees can coordinate projects, connect business systems, share information, and act on notifications without moving constantly between email and specialized tools. The product traces its origins to Tiny Speck, the company created by Stewart Butterfield and collaborators after the closure of the multiplayer game Glitch. During the development of Glitch, the team built internal communication software to manage distributed work. That internal tool evolved into Slack. A preview release in 2013 generated strong early interest, helped by invitations, customer feedback, word of mouth, and a free entry tier. Slack subsequently expanded from technology startups and creative teams into larger enterprises, public-sector organizations, education, media, retail, financial services, manufacturing, and other industries. Slack's growth model combined product-led adoption with paid plans for additional history, administration, security, compliance, and enterprise functionality. Its integration ecosystem became a central part of the proposition, connecting the service with tools for software development, customer support, file storage, identity management, project work, analytics, and sales. This made Slack useful as a cross-functional information hub and also created network effects within organizations: once multiple teams used a shared workspace, the cost of returning to fragmented communication increased. The company acquired HipChat and Stride from Atlassian in 2018, with the services scheduled for closure and their users encouraged to move to Slack. Slack then became publicly traded through a direct listing on the New York Stock Exchange in June 2019 under the symbol WORK. At the time of its public-market filing, the company reported more than 10 million daily active users across more than 600,000 organizations in over 150 countries. The listing gave Slack a prominent public profile while it continued competing with Microsoft Teams, Cisco Webex, Google Chat, and other collaboration products. Salesforce announced an agreement to acquire Slack in December 2020. The transaction closed on July 21, 2021, and Slack became a Salesforce subsidiary. The acquisition placed Slack at the center of Salesforce's strategy for a digital headquarters, linking conversations and workflows with customer relationship management, marketing, service, analytics, and other enterprise applications. Slack continues to operate as a distinct product brand while being integrated into Salesforce's broader platform strategy. Its marketing has consistently emphasized how work gets done rather than presenting a narrow list of technical features. Campaigns such as “Where Work Happens” used tailored creative for different cities and professional audiences, while later hybrid-work advertising used customer stories to demonstrate cross-functional collaboration in industries beyond technology. The brand's current strategic territory includes channels and messaging, workflow automation, searchable organizational knowledge, app integrations, enterprise administration, and AI-supported discovery and productivity. Specific current leadership, ownership structure beyond Salesforce, and present-day user or financial metrics are not enumerated here where the supplied sources do not establish them reliably.

History

Slack began inside Tiny Speck, the company formed by Stewart Butterfield and collaborators after the team behind the online game Glitch moved into a new project. While developing Glitch, the company relied on an internal communication system that brought together conversations, files, and team coordination. When Glitch was discontinued, that internal tool appeared to have broader commercial potential than the game itself. Tiny Speck developed it into Slack, an acronym derived from “Searchable Log of All Conversation and Knowledge.” The service entered preview in 2013. Its initial adoption was driven by teams willing to experiment with a new alternative to email, particularly startups, software groups, design organizations, and other knowledge workers. Slack's free access tier reduced the barrier to trial, while persistent channels and searchable history addressed a common problem in growing companies: important decisions were distributed across inboxes, meetings, and private conversations. Early customer feedback shaped the interface and the expanding integration model. Slack's product strategy developed around three connected ideas. First, conversation should be organized by project, team, or subject rather than trapped in individual inboxes. Second, the communication layer should connect to the other software that organizations already use. Third, automation and search should turn accumulated conversations into an operational resource. These principles supported expansion from messaging into workflow tools, enterprise identity and administration, external collaboration, structured documents, and AI-oriented knowledge discovery. The company grew through a mixture of user recommendation, product-led adoption, content and community activity, and targeted marketing. Its freemium approach allowed individuals or small teams to begin without a procurement process, while paid plans added longer message history and more advanced administrative, security, and compliance capabilities. The integration ecosystem also encouraged internal spread: a team might first use Slack for chat, then add engineering alerts, customer-service notifications, file storage, calendars, project-management tools, and automated approvals. In July 2018 Slack acquired HipChat and Stride from Atlassian. Both services were planned for closure, and the transaction helped consolidate users around Slack while removing two products from a major competitor's portfolio. Slack later pursued a direct public listing. It started trading on the NYSE on June 20, 2019 under WORK, giving investors access to the company without a traditional primary IPO offering. Its public filings described a rapidly expanding global user base, including more than 10 million daily active users and more than 600,000 organizations across over 150 countries. Competition intensified as Microsoft Teams, Cisco Webex, Google Chat, and other platforms combined messaging, meetings, file sharing, and productivity applications. Slack differentiated itself through its channel-based interface, developer ecosystem, searchable archive, extensive integrations, and a brand voice that treated workplace communication as a cultural and organizational problem as well as a software category. Its advertising often showed recognizable work situations instead of relying solely on feature demonstrations. Salesforce announced its acquisition of Slack on December 1, 2020. The deal was structured as cash and stock and represented Salesforce's largest acquisition. After the necessary approvals, the transaction closed on July 21, 2021. Slack became a Salesforce subsidiary and a strategic component of Salesforce's concept of a digital headquarters, connecting employee collaboration with customer, sales, service, marketing, analytics, and automation systems. Following the acquisition, Slack remained a distinct brand and product while its role broadened from team messaging toward a work operating layer. The company promoted hybrid-work use cases, workflow automation, enterprise collaboration, searchable knowledge, and integrations across organizational systems. It also introduced or expanded structured work features such as canvases and directory capabilities, including functionality associated with the Rimeto acquisition and later presented as Slack Atlas. The brand's long-term challenge is to remain differentiated as workplace software converges around messaging, meetings, documents, automation, and artificial intelligence.

2022
Hybrid-work repositioning
[6]Slack hybrid-work campaign reportbusinessinsider.com
Slack promoted customer stories from organizations outside its traditional technology audience to demonstrate hybrid and cross-functional work.
2021
Acquisition closes
[5]Salesforce closes $27.7 billion acquisition of Slackfinance.yahoo.com
Salesforce completed its acquisition of Slack on July 21, making Slack a subsidiary and ending its independent listing.
2020
Salesforce announces acquisition
[8]Slack merger agreement filingsec.gov
Salesforce and Slack entered an agreement for Salesforce to acquire Slack in a cash-and-stock transaction.
2019
Direct public listing
[4]Slack IPO: What You Need to Knowinvestopedia.com
Slack Technologies began trading on the NYSE under WORK through a direct listing.
2018
HipChat and Stride acquisition
[1]Slack (software)en.wikipedia.org
Slack acquired Atlassian's HipChat and Stride services and planned their shutdown and user migration.
2017
Where Work Happens campaign
[3]Slack 2017 Where Work Happens Advertising Campaignrussellshawdesign.com
Slack ran a global campaign using localized and career-specific creative to present collaboration as the place where modern work happens.
2013
Slack enters preview
[9]Slack enters previewbdow.com
The workplace communication product began an external preview and attracted early teams through invitation-based adoption and word of mouth.
2009
Tiny Speck is founded
[1]Slack (software)en.wikipedia.org
Stewart Butterfield and collaborators founded Tiny Speck, the company whose internal communication technology later became Slack.

Products and positioning

A digital headquarters and work operating layer for organizations, combining team communication with enterprise search, integrations, automation, and workflow coordination.

Team collaboration · 2013
Slack core workspace
The core Slack workspace provides channels for organized group discussion, direct messages for individual or small-group communication, file sharing, notifications, threads, reactions, and searchable conversation history. It supports both informal coordination and structured project work, allowing teams to retain context and make information available beyond a single meeting or inbox. Free and paid plans have historically served different levels of usage, administration, security, compliance, and retention.
External collaboration
Slack Connect
Slack Connect extends Slack conversations beyond one organization by allowing approved external parties to communicate in shared channels or direct messages. It is designed for work with customers, agencies, suppliers, partners, and other professional contacts while preserving administrative controls. The offering reflects Slack's broader ambition to make the workspace a communication layer spanning organizational boundaries rather than an internal-only chat system.
Workflow automation
Workflow Builder
Workflow Builder enables organizations to automate recurring processes inside Slack, such as intake requests, employee questions, reminders, approvals, and notifications. Workflows can connect structured forms or triggers with messages and actions, reducing manual coordination for routine tasks. It represents Slack's shift from a conversation product toward an operational platform in which teams can initiate and complete business processes from the same environment.
Enterprise collaboration
Slack Enterprise Grid
Enterprise Grid is Slack's large-organization architecture for managing multiple workspaces under shared administrative, security, identity, compliance, and governance controls. It is intended for complex enterprises that need organizational separation while retaining discoverability and collaboration across business units. The product supports Slack's enterprise positioning and provides capabilities beyond those required by a small independent team.
Software integrations
Slack app platform and integrations
Slack's app platform connects the workspace with external business systems, including developer tools, file services, calendars, customer platforms, project software, identity providers, and notification systems. Integrations can post updates into channels, allow users to take actions, or trigger workflows. The ecosystem is strategically important because it embeds Slack in existing work processes and makes the service more useful as the number of connected teams and systems grows.
Employee directory and knowledge · 2021
Slack Atlas
Slack Atlas is an employee directory and profile capability associated with Rimeto, an employee-directory startup acquired by Slack in 2020. It was presented as an optional Slack feature in 2021, helping users understand organizational structure, roles, expertise, and reporting relationships. The offering extends Slack's value from message exchange toward discovering who in an organization can help with a particular question or task.

Controversies

2021
Slack faces criticism over Connect DMs feature
In April 2021, Slack introduced a feature called Connect DMs, which allowed messaging across groups. The feature drew social-media backlash. Users criticized it over possible harassment and privacy issues, and called for a block feature to be added. The criticism centered on the risks users associated with cross-group messaging rather than on any specific reported incident.
Source

Marketing campaigns

2022Hybrid work customer-story campaign
United States · United Kingdom · Global
Slack used case studies involving Deliveroo and Kiva to reposition the brand for hybrid work and to show applications outside its traditional technology audience. The stories depicted geographically distributed and cross-functional teams coordinating complex operations through Slack.
Outcome. The campaign supported Slack's effort to broaden its category definition from workplace messaging to collaboration and coordination across industries.
Source
2017Where Work Happens
United States · Germany · Nashville · Salt Lake City · Berlin
Slack's integrated global campaign used the central idea “Where Work Happens” and adapted it for specific cities, professions, and local contexts. The program combined outdoor advertising, print, podcasts, and other media, with custom artwork presenting collaboration and modern work as a vivid destination. Nashville, Salt Lake City, and Berlin were identified as test markets for localized executions.
Outcome. The campaign reference reports increases in unaided awareness and search activity in the named test markets, but the figures are not independently validated here.
Source
The Big Meeting
Global
A comedic musical advertisement dramatized a sales team preparing for a customer meeting. Its creative premise contrasted unnecessary complexity with Slack's ability to bring files, information, colleagues, and preparation into one collaborative environment.
Outcome. The campaign communicated Slack's productivity positioning through entertainment and feature storytelling rather than a conventional software demonstration.
Source

Brand decisions

2021
Introduce Slack Atlas as an optional capabilityGeneration change
Background
Slack acquired Rimeto, a startup focused on employee directories and profiles, to expand the platform's organizational knowledge capabilities.
Action taken
Slack launched Rimeto-related functionality as an optional feature called Slack Atlas.
Aftermath
The feature broadened Slack's role from communication toward employee discovery and organizational context.
Source
2020
Agree to Salesforce acquisitionM&A
Background
Salesforce sought to strengthen its collaboration and digital-work strategy, while Slack faced intensifying competition in workplace communication software.
Action taken
Slack agreed to be acquired by Salesforce in a cash-and-stock transaction announced on December 1, 2020.
Aftermath
The deal closed on July 21, 2021, and Slack became a Salesforce subsidiary. The transaction was reported as approximately $27.7 billion in contemporary coverage.
Announced transaction value. approximately $27.7 billion (Announced December 1, 2020; closed July 21, 2021)
Source
2019
Use a direct listing for public-market entryOther
Background
Slack wanted its existing shares to begin trading publicly without using a conventional underwritten IPO process.
Action taken
Slack listed on the New York Stock Exchange under WORK on June 20, 2019 through a direct listing.
Aftermath
The listing made Slack a public company and established a market reference for its shares before its later acquisition by Salesforce.
Source
2018
Acquire and retire HipChat and StrideM&A
Background
Atlassian's HipChat and Stride competed in workplace collaboration, while Slack sought to expand its user base and consolidate its position in team communication.
Action taken
Slack acquired the services and announced plans to shut them down in February 2019, with users encouraged to migrate to Slack.
Aftermath
The transaction removed two competing Atlassian services and offered their users a migration path into Slack.
Source

Recent events

2022
Slack launches hybrid-work brand campaign[6]Slack hybrid-work campaign reportbusinessinsider.com
Campaign
Slack used customer stories from Deliveroo and Kiva to broaden its positioning beyond technology companies and explain collaboration in hybrid-work settings.
2021
Salesforce completes acquisition of Slack[5]Salesforce closes $27.7 billion acquisition of Slackfinance.yahoo.com
M&A
The Salesforce acquisition closed on July 21, 2021, making Slack a Salesforce subsidiary and ending its independent public-company status.
2020
Salesforce announces agreement to acquire Slack[8]Slack merger agreement filingsec.gov
M&A
Salesforce announced a cash-and-stock transaction to acquire Slack, subject to regulatory and shareholder approvals.
2019
Slack begins trading through a direct listing[4]Slack IPO: What You Need to Knowinvestopedia.com
Other
Slack Technologies began trading on the New York Stock Exchange under WORK through a direct listing rather than a conventional underwritten IPO.
2018
Slack acquires HipChat and Stride from Atlassian[1]Slack (software)en.wikipedia.org
M&A · Other
Slack acquired Atlassian's HipChat and Stride collaboration services and planned to discontinue them, encouraging users to migrate to Slack.

Related entries

Salesforce