How many daily active users does Slack have?

Daily active users globally? → Yes

Across different OS and all types of devices? → Yes

We know that it's a platform designed to facilitate communication and collaboration within teams, departments, and even with external partners.

Mainly used for business purposes.

World Population ~ 8B

Slack is most probably not used in China, North Korea and Russia. Together, their population ~ 1.5B. Potential global population using Slack = 8B - 1.5B = 6.5B.

People mainly above the age of 18 (20) and below the age of 65 years (mainly the working population) will use Slack for work. Also, assuming uniform population distribution across age groups and life span of 80 years, potential global population using Slack = (45/80) * 6.5B = 3.65625B or 3.6B.

People need internet connection to be able to use Slack. Assuming internet penetration of 60%, potential global population using Slack = 60% of 3.6B = .6 * 3.6 = 2.16B,

Assuming mostly white collar workers use Slack and split between while collar and blue collar workers is 45:55, potential global population using Slack = 45% of 2.16B = 0.45*2.16B = 0.972B or 970M.

Slack’s major competitors are Microsoft Teams, Google Chat, Mattermost and Discord. Lets assume Microsoft Teams and Slack hold about 60% of the market share with 40% and 20% split respectively, potential global population using Slack = 20% of 970M = .2*970 = 194M or 190M.

Since, Slack is mostly used for business purposes, folks working daily need to use Slack to collaborate.

So, assuming 60% - 80% of Slack’s users use it daily 

⇒ Considering 80%, daily active users of Slack = 80% of 190M or 0.8190M = 152M 

⇒ Considering 60%, daily active users of Slack = 60% of 190M or 0.6190M = 114M