Slack sized up for bid by Amazon, among others, valuing it at $9bn

Slack’s Vancouver office

Slack Technologies, a corporate messaging and collaboration software startup, has received inquiries about a potential takeover from technology companies including Amazon, Bloomberg is reporting, in a deal that could value the company at $9bn.

San Francisco-based Slack has raised more than $500m from venture capitalists and was valued at $3.8bn at its last private financing round a year ago. Its messaging and collaboration platform also integrates with a wide variety of business software – such as Salesforce and Microsoft Skype – so that employees can do all their work within Slack.

Slack is the product of entrepreneur Stewart Butterfield’s second failed attempt to make a video game. His first, called Game Neverending, had a photo-sharing feature that became more popular than the game. It became Flickr, which was sold to Yahoo for $25m in 2005. In 2011, he introduced another game, Glitch, in which people cooperated to build a shared world. (Misbehaving players got a timeout.) At its height, the game was costing the company $500,000 a month and bringing in $30,000, so Butterfield closed it in 2012. A few employees stayed on to build out the messaging platform that Glitch engineers had used to talk among themselves; that project became Slack.