Slack Revenue and Usage Statistics (2021)

David Curry

Updated: May 6, 2021

In 2011, indie game studio Tiny Speck launched Glitch, an anti-combat MMO which failed to gain any interest. Due to the team being located in three locations, it built an instant-messenger during development to better communicate online, which became a hub of activity.

Seeing the opportunity, co-founder and CEO Stewart Butterfield shut down Glitch in 2012 and began to work full-time on the messaging app, which would become Slack.

This was Butterfield’s second time pivoting a failed game project into a successful tech product. In 2002, his video game studio Ludicorp started work on Game Neverending, which never made it to launch. Some of the game’s features were used to create Flickr, which he sold to Yahoo in 2004 for $25 million.

It is worth noting the similarities between Slack’s founding and Discord. Both were run by entrepreneurs who had made millions from their previous venture (Flickr and OpenFeint) and then released a video game to muted reception. That failure inspired both to launch communication tools.

Originally beta testing the app with a few organisations, Butterfield saw the potential of Slack as an answer to the many disparate ways employees communicated. Instead of meetings, e-mail threads and phone calls, everything could be done through one application.

According to Slack, using the app reduces emails by 32 percent and meetings by 27 percent.

After a year of privately testing the app, Slack launched publicly in February 2014. It was an instant success, receiving 8,000 requests in the first day and 15,000 by the second week. Slack had to stagger the launch, as it added more server capacity to meet demand.

As Slack added more organisations, word of mouth accelerated demand, as many media organisations were the first to use the app and wrote positive reviews of it. It grew at a rate of five to 10 percent a week in the first year. Slack reached unicorn startup status in 2014, and its value almost trebled the next year when it was valued at $2.8 billion.

Slack’s first few years were led by the app’s user experience, which was easier and modern compared to Hipchat or Campfire, the two other notable online chat tools used at the time. In 2016, Slack debuted a flurry of new features to push it beyond the competition, including an app and bot ecosystem.

The use of bots made it easier for managers to relocate most of their operations to Slack. Managers could track employee time off, send surveys, receive and forward emails, and talk to clients through the app.

Business tools, such as Google Drive, GitHub, Asana, Zapier and Salesforce, are all integrated into Slack as well. Some have built an app inside Slack, allowing users to stay on the platform, while others simply inform users of any changes or updates to files.

There are over 2,000 apps and 750 bots on the Slack App Directory.

The future looked great for Slack, and then Microsoft announced Teams.

For the past three years, Slack and Microsoft have gone back and forth at each other, with most of the barbs coming from Slack. Butterfield has said Microsoft is “unhealthily preoccupied with killing [Slack]” and recently filed an anti-trust lawsuit, due to Microsoft use of the Office 365 platform to accelerate Teams adoption.

While Slack has grown steadily in daily active users (DAUs), from six million when Teams launched to 12 million in 2020, Microsoft Teams has surged ahead, currently at 75 million DAUs. This is partly due to Microsoft marketing Teams as a catch-all solution for people and organisations affected by COVID-19.

Butterfield has also accused Microsoft of “fudging the numbers” by saying a Teams user is active simply for having the app open or using it for less than 10 minutes per day. Microsoft has refuted those claims.

Microsoft appears set on making Teams the communications platform for everyone, but that doesn’t necessarily mean Slack will be crushed. As Butterfield said in 2019, 70 percent of the company’s top 50 biggest customers use Office 365 in tandem with Slack.

It has taken some of the shine from Slack however, which was the darling of the tech industry. From a high of $23 billion post-IPO, Slack’s value dropped to $17 billion. Salesforce announced its intention to acquire Slack for $27.7 billion on December 1, 2020.

We have collected data and statistics on Slack. Read on below to find out more.

Slack key statistics

  • Slack generated $902 million revenue between March 2020 to April 2021, a 43 percent increase year-on-year
  • Net loss also decreased from $567 million to $292 million in that same period
  • Slack has 12 million daily active users and 156,000 organisations subscribe to the app
  • In December 2020, Slack was acquired by Salesforce for $27.7 billion

Slack overview

Launch date 14 August 2013
HQ San Francisco, California
People Stewart Butterfield (co-founder, CEO), Cal Henderson (co-founder, CTO)
Business type Public
Industry Business communication

Slack revenue

Year Revenue
2014 $12 million
2015 $30 million
2016 $100 million
2017 $200 million
2018 $221 million
2019 $401 million
2020 $630 million
2021 $902 million

Note: Slack’s fiscal year runs from March to April. Q4 2021 results were published in March 2020, so yearly revenue for 2020 consists of April 2019 to March 2020. 

Sources: Slack, Business Insider

Slack profit

Year Profit
2017 ($146 million)
2018 ($140 million)
2019 ($138 million)
2020 ($567 million)
2021 ($292 million)

Note: Parentheses indicates loss. 

Sources: Slack, VentureBeat

Slack users

Year Users
2015 2 million
2016 4 million
2017 6 million
2018 8 million
2019 12 million

Note: Slack has not updated its daily active user figures since 2019. It had 10 million concurrents during the first coronavirus pandemic in April 2020 

Sources: Slack, Fast Company, The Verge

Slack paying customers

Year Paying customers
2017 50,000
2018 60,000
2019 88,000
2020 112,000
2021 156,000

Source: Slack

Slack organisations

Year Organisations
2014 30,000
2015 60,000
2016 1200,000
2017 330,000
2018 450,000
2019 640,000
2020 750,000

Note: This accounts for all organisations which use Slack, many of which do not pay for it 

Sources: Slack, Fast Company, The Verge

Slack valuation

2014 $1.1 billion
2015 $2.8 billion
2016 $3.8 billion
2017 $5 billion
2018 $7.1 billion
2019 $23 billion
2020 $17 billion

Note: Salesforce acquired Slack for $27.7 billion in December 2020, a $10 billion premium on its market cap 

Sources: VentureBeat, TechCrunch, FT

Slack funding (total)

2011 $15 million
2014 $164 million
2015 $283 million
2016 $491 million
2017 $904 million
2018 $1384 million

Source: Crunchbase

Slack vs Microsoft Teams: DAUs and Organisations

Note: Some of Microsoft Teams surge in DAUs is due to non-corporate usage, which may not stick post-COVID. Slack counts both free and paid subscribers for organisation total.

Slack FAQ

How many Fortune 100 companies use Slack?

According to Slack, 65 of the Fortune 100 use Slack in some capacity

Which are some of the largest organisations using Slack

IBM, Amazon, PayPal and Airbnb all use Slack

How active is the average Slack user?

Users are active for 90 minutes per day on weekdays, according to Slack in 2019

How much does Slack reduce email?

According to Slack, using the app reduces emails by 32 percent and meetings by 27 percent

How many messages are sent on Slack per week?

1.5 billion messages are sent on the service every week

How many developers are registered on Slack?

Over 500,000 developers use Slack

How many apps are built for Slack

There are 2,000 apps and 750 bots available in the Slack App Directory

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