Slack’s strapline is ‘Be less busy’ and it aims to bring different types of communication, such as email, into one place.
In November 2015, at barely two years old, it received funding valuing it at an astonishing $3.8bn (£2.6bn) and its website suggests it is contributing to space exploration: NASA is a client, while its homepage features a robot exploring Mars.
It has been called the fastest-growing business application of all time and was founded by Canadian Stewart Butterfield, who sold his first major business, Flickr, to Yahoo for an estimated $22m to $25m (£15m to £17m) in 2005.
Former colleague Bradley Horowitz, now at Google, invested in the business and it has 2.7 million daily active users, with businesses including eBay, LinkedIn and Buzzfeed using it. Businesses report that they send 50% fewer emails as a result of using Slack.