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February 1, 2023updated 07 Mar 2023 5:09pm

What is Slack?

Could Slack be useful in your business?

By Alexander Sword

Slack is a cloud collaboration tool that lets users communicate and share documents. Upon its launch in 2013, the Canadian company was considered a ‘Unicorn’ – meaning that it was one of the fastest companies to receive a billion-dollar valuation.

Slack eliminates the need for email or group SMS in the workplace, providing a platform where colleagues can communicate and share files, images, PDFs, documents and spreadsheets. Services such as Google Drive and Dropbox can be integrated with Slack for more convenient collaboration.

Slack has steadily evolved into a community platform, allowing communities, groups or teams to come together via a specific URL or invitation sent by a team admin or owner. Communities are arranged by topics which a group of people or a team may be interested in discussing.

Slack mobile app
Slack mobile app (Image: Shutterstock/Rafapress)

How many people use Slack?

The program was initially developed as an internal tool for the game developer Tiny Speck. It has since seen rapid growth, reaching 500,000 daily active users within its first year of operation. As of December 2022, its active user base is estimated at around 12 million people.

Is Slack free?

Slack can be used for free, but it has limited functionality. As with many business software programs, packages are priced per user and increase in price with the range of available features. The range of packages is as follows:

  • Free
  • Pro: £5.75 per user per month
  • Business+: £9.75 per user per month
  • Enterprise: custom pricing

Is Slack safe?

In 2015, Slack disclosed that it had been hacked over the course of four days. The software maker confirmed that some users’ email addresses, usernames, encrypted passwords and phone numbers had been compromised. Since the attack, Slack has deployed two-factor authentication to its service.

More recently, on 29 December 2022, hackers gained access to Slack’s externally hosted Github repository which held private software code. However, none of this data included customer information or code that is core to the operation of the service.

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Slack is just one of a number of collaborative communication apps on the market. Others include:

Microsoft Teams

Microsoft offers its own workplace comms app, which can be neatly integrated with the Office 365 suite of products. Despite entering the market as a challenger, Microsoft’s power as a company has allowed it to become one of the most popular products in the industry.

Teams is set to introduce generative AI software ChatGPT in 2023.

Google Workspace

Along with its free productivity tools such as Gmail, Docs and Sheets, Google offers a paid business service with greater security, large video meetings and increased storage.


Despite not being a professionally focused product (though it does have a Business app), Whatsapp remains a popular app for small businesses to communicate, thanks to its ease of use, end-to-end encryption and ubiquity in many countries.


Rocket.Chat is an open-source collaboration software. It has many features in common with Slack but its open-source design means that it can be hosted on a private server, which is an advantage for data security but can be less easy to use.


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