Slack

Slack, messaging app for businesses cofounded by Canadian entrepreneur Stewart Butterfield and owned by the technology company Salesforce. Slack is celebrated for its channel-based platform, which can help facilitate communication, collaboration, and productivity among teams. The company has been described as a unicorn, a term used for privately held start-ups that are valued at more than $1 billion. Slack Technologies is headquartered in San Francisco.

Features

Slack has several key features that both support its functionality and increase its appeal to users. In particular, Slack allows users to exchange instant messages in one-on-one and group formats and to communicate in “channels” dedicated to a specific team or topic. Users can share documents and other files, engage in audio or video calls, and search archives of past messages.

Slack hosts integrations with other frequently used platforms and apps, including Zoom, Google, and Amazon Web Services (AWS). Integration with Google Drive, for example, allows for efficient document sharing and editing while integration with Dropbox enables detailed previews of files. Giphy integration offers the ability to communicate using GIFs. Users can “pin” messages to the top of a chat, whether in a channel or a group chat, making for quick and easy access to important links and messages at later times.

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Historical developments

When Slack was first created, it was not intended to be public facing. In fact, the app was originally developed as an internal communication tool for Butterfield’s company Tiny Speck, particularly for those working on the quirky online multiplayer game Glitch. Although Glitch was generally well received, its creators found the game to be expensive and unwieldy. As a result, in 2011 Glitch was briefly “unlaunched” in order to improve key features. The following year the game was shut down permanently. Left with about $5 million from investors but no product, Butterfield and his team considered marketing their internal communication app, which Glitch’s developers had found to be especially useful for sending and receiving individual and group messages and for quickly searching through archives of past conversations.

Butterfield’s company Slack Technologies (founded in 2009) began work on its namesake app in 2012, building on and improving Glitch’s internal communication tool. The initial rollout was shaky. The team relied on friends to test the app at their companies and often found its functionality difficult to describe. Slack failed its first test at scale: a rollout to a 120-person start-up. The app subsequently underwent eight additional months of development, after which point it was ready to enter the market.

Slack’s preview release appeared in app stores in August 2013; the app was an instant hit. Initially, Butterfield said, workers downloaded the free software without receiving permission from their IT departments. Slack remained live for customer testing until its official release in February 2014, building so much demand that the company earned $1 million in subscriptions in just three days. Butterfield attributed Slack’s success to not only listening to user feedback but also actually implementing it—even if the feedback was “contrary to [the company’s] vision.”

By 2015 Slack Technologies was valued at more than $1 billion, and in 2019 the company went public through a direct listing, meaning no new stocks were offered and only existing shares became available. Nonetheless, after the first day of trading, Slack Technologies’ market value was about $19.5 billion. In July 2021 data management giant Salesforce completed its acquisition of Slack Technologies for nearly $28 billion. Butterfield described the merger as part of a “historic shift to a digital-first world” in the wake of the COVID-19 pandemic, which had caused many companies to shift employees to remote, as opposed to in-office, work. In December 2022 Butterfield announced that he would be leaving Slack; his departure coincided with the resignation of Bret Taylor as co-CEO of Salesforce.

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In 2021 Slack launched its “Huddles” feature, which offers users the ability to quickly jump into calls and leave them while keeping the line open. Butterfield intended for the feature to imitate a simple across-the-desk workplace chat, having it be more informal than a scheduled video or phone call. In 2020, to improve its ability to compete with Microsoft Teams, the service announced a partnership with AWS to power its voice and video call features.

Incorporation of AI

In February 2024 Slack launched Slack AI, an artificial intelligence (AI) feature that can answer questions, suggest search terms, and summarize user conversations. That same year the company faced backlash from some users who criticized the app’s user agreement, which theoretically allowed Slack to train AI with users’ conversations. Slack Technologies maintained that it did not use customer data to train AI.