How Slack brought the group chat to work

Most enterprise software is shitty. It’s clunky and unintuitive; the user interface is an afterthought. It seems obvious that the people who make these apps (hi Concur!) know that only a few people need to be convinced to make the purchase, and user interface matters a lot less than business-critical features. The average employee might hate the app, but that doesn’t matter. They’re going to use it anyway.

That’s one reason why Slack, the workplace chat app that formally launched 10 years ago today, is so unusual. Slack was the rare piece of enterprise software that spread through word of mouth, because it was actually, you know, good.

“What Slack brought in was that it was fun to use,” says Javier Soltero, who previously oversaw Microsoft Outlook and Google’s Gchat and Gmail. “It’s not an engineering thing. It’s the art of product development, honestly. That made all the difference, because it made people feel like interacting via Slack was not just about sending words in real time. It let people express themselves and create a sense of culture.”

Slack is known for bringing group chats to the workplace, but it also kickstarted a major shift in how we socialize that had ripples beyond the office. A decade on, the group chat is always humming in the background, whether it’s your family texting you during the day, or your co-worker sending you a late-night DM. Sure, Slack made work feel more conversational, accessible, and fun. But now, fun also feels more like work.

Famously, Slack did not begin as an enterprise product — it was supposed to be a video game, Glitch. (Glitch was arguably an attempt at a metaverse before that was cool.) When it became clear to then-CEO Stewart Butterfield in 2012 that Glitch didn’t have enough users to support a business, the company pivoted within weeks; it had built an internal communication software to coordinate the game. That became Slack. 

“I can remember Stewart’s board deck, before we started building,” says Johnny Rodgers, a founding employee and the former principal engineer at Slack, who departed in 2023. “His pitch was, ‘I think this can be a $100 million business.’ And when I left the company, there was $2.5 billion in revenue.”

Slack was the right app in the right place at the right time. By the early 2010s, people who had been using chat apps and text messages in their private lives for years were a significant part of the workforce. And people were already using consumer chat at work — Soltero tells me he heard stories about Wall Street traders using AOL Instant Messenger, for instance. The Blackberry and, later, iPhone set the stage for more widespread adoption. 

Chats are more real time than email, without being as urgent as a phone call. “There’s also the idea that I’m on the move, but I can still respond to you,” says Soltero, who now leads the enterprise business at Canva. And with the introduction of the iPhone, texting became much more commonplace, he says.

Slack’s design pulled from elements of those kinds of consumer products: channels, status messages, availability indicators, telling users when someone was typing. Slack felt familiar. And unlike competing workplace apps, like HipChat and Campfire, which were mostly meant for engineering teams, that meant just about anyone could use it.

“The thing that made Slack instantly feel so familiar — and beloved — was actually the fact that it was bringing this messaging paradigm from your consumer life to the workplace for the first time,” says Slack’s chief product officer Noah Weiss. 

Slack also had a simple pitch: the way we were communicating at work took too much energy. 

Before Slack, most of us used some combination of email, phone calls, and in-person (or video) meetings to coordinate work. Email threads can be annoying to read, particularly if you’re dropped into the middle of a conversation. Phone calls are best for one-on-one conversations. Meetings are, frankly, both time-consuming and annoying. What Slack provided was a casual and asynchronous way for co-workers to talk. It also had a log of those messages, so any employee dropping in on their first day had access to an archive of company history.

Slack had another advantage: one of the founders, Butterfield, was older than the typical startup founder at the time. He’d worked in tech since the dot-com bubble, co-founded Flickr, and had an extensive network as a result. Early users were within the personal networks of Slack employees.

“It’s like, really, really close colleagues,” says Ali Rayl, who was a senior vice president of product at Slack. “We’re like, ‘Hi, we’re building this. It may be total garbage. It works perfectly for us, a team of eight people building this product. Does it work for you?’”

Rayl was, at the time, the head of customer experience, and, unusually for a tech company, she had a seat at the table for major decisions, says Rodgers. Slack wasn’t customer-focused in a buzzword-type way — customer support had real power at the company, which was crucial in the early days, when everything was breaking.

Slack moved on to a bigger beta with a company that was already using Skype chat heavily as a work tool: Rdio, a hip streaming music service that was competing with Spotify at the time. Displacing Skype wouldn’t be easy, since Rdio was founded by guys who made their fortune with Skype. 

So Slack built new tools: it made channel descriptions, which let a user see what a channel’s about without joining it, and private channels. Eventually, Rayl knew Slack had overtaken Skype chat because users were being introduced to Slack on their first day at Rdio.

Slack was not the only text-based communications software. Besides Skype chat and Gchat, there were also other startups: HipChat, Yammer, and Campfire. Slack tested out these products to see what didn’t work with them and discovered two things they could improve on: notifications and keeping a person’s place when they switched between mobile and desktop. That meant that even though Slack wasn’t doing head-to-head marketing — or indeed, any marketing at all — customers kept leaving other platforms and coming to Slack because it worked better. There were so many people defecting from other clients that the product roadmap had to be shifted to make importing data easier, Rayl says.

By the time Slack had its official launch on February 12th, 2014, it was a buzzy startup that made software for other buzzy startups. The majority of its customers were in the tech industry. That’s also how it spread — through people who were, for instance, in developer relations and had a lot of personal connections.

“Pretty soon after we launched, I remember being in the coffee shop around the corner here in Vancouver, and seeing people using Slack,” Rodgers says. Normal people using Slack was “totally thrilling,” he says.

Because so many people were using Slack in their work lives, some of its features started leaking out. For instance, Slack introduced emoji reactions — to reduce noise, people could just respond with a checkmark to show they’d read something. This spread from Slack back into consumer software. Tapbacks on iMessage feel like a response to Slack. Even Facebook, which had a like button, didn’t add other options until later. “I think we were the first to do it on a broad basis within the workplace,” Rodgers says. “We saw reactions show up everywhere within a couple years. I can remember one day opening GitHub of all things, and they had a reaction bar.”

Slack was casual and fun because the startup itself was casual and fun — after all, it had started as a gaming company. Being able to upload custom emoji, another Slack feature, let workplaces personalize. (If you type :jeeves: into the Vox Media Slack, you will see an emoji of my cat.) Chat itself also was less formal than email or phone calls as a form of communication, which started to change workplace norms in ways the team hadn’t anticipated. For instance, if the CEO made an announcement people didn’t like, they might react with a negative emoji. 

By this time, group chats had become ubiquitous — perhaps because people were withdrawing from the audience of maybe-hostile strangers that social media promised. Discord was released in 2015 and began gobbling up chunks of the consumer market as gamers switched from IRC (Internet Relay Chat). New questions began to arise about emojis and private channels. Nothing suggests that a form of communication has won like pontificating about the etiquette of sending a DM that only says “hi.”

Slack’s success proved that people wanted group chat at work. Around the time Slack was working on an enterprise version, which shipped in 2016, for customers such as Comcast and IBM, Microsoft woke up and realized a startup had eaten its lunch. Because Microsoft could bundle its competitor — Teams — with Word, Excel, and Outlook, it had a distribution advantage.

Slack went public in June 2019 through a direct listing, five years after its product was officially introduced to the world. Sure, this was partly about letting investors exit, but it was also meant to reassure customers that Slack wouldn’t get eaten by another big company, says Rodgers. A little more than a year later, Salesforce announced it was acquiring Slack. By then, the emergence of the coronavirus pandemic had supercharged remote work, making group chat a necessity.

Since the acquisition, a lot of the founding team has left. That often happens after an acquisition; some of those people had been working together on Slack for the better part of a decade or longer. The two companies were also very different culturally, Rodgers says. 

Throughout its history, Slack the product has reflected Slack the company. The company tended to increase in size proportionally to the size of its customers. When it was a startup, it mainly had startup customers. When it was a small company, its customers were small companies. That meant a direct connection between the company and the product; after all, the product had been initially built to meet the company’s needs. 

So what’s in store with Salesforce? Weiss, the product officer, is looking for ways to sprinkle AI into the product. “If you think about it, it is the most incredible unstructured corpus of knowledge and information you could ever imagine at a company,” he says. “Being able to do large language models on top of that implicit knowledge scattered for so many years in Slack is just an unbelievable opportunity to deliver productivity and intelligence to every organization without them having to do any work at all, right?”

Weiss sees a tremendous opportunity with AI. “Slack is the most natural, conversational interface, and now, having these tools lets you talk to your team, and, naturally, you can talk to these tools, all in an interface that was designed to do this,” he says. “So when I think about the next decade, it’s not the only thing I’m excited about, but it’s the thing I’m most excited about.”

The question of who will own the chat market still looks uncertain. The European Union is now investigating Microsoft after Slack filed an antitrust complaint about Teams. Discord laid off 17 percent of its employees in 2024, following previous cuts in August — suggesting, variously, trouble or streamlining for an IPO or a sale. (Discord had deal talks with Microsoft that came to nothing.) WhatsApp, iMessage, Telegram, and Signal all occupy important parts of people’s personal — and sometimes professional — lives. 

Slack’s idea won. The work group chat is here, and it’s always on, even when you’re asleep. Sure, Slack has made features to deal with that (delayed send, do not disturb, warnings that you are messaging after work hours). But those features underscore the point: our work lives and private lives are bleeding together.

Slack was initially marketed as an email killer. We still have email. Slack’s Huddles feature was meant to spare people Zoom fatigue. We still have Zoom. Maybe Slack means less time in meetings, but that seems difficult to prove. All I can say for sure is that I’ve spent a lot of time over the last decade in my work group chat — and now that it’s a part of my routine, I will probably spend a lot more in the coming 10 years.