Slack CTO talks growth, email and sci-fi

We speak to Slack CTO and co-founder Cal Henderson about about future plans and the threat from Microsoft Teams

“I don’t think email is going to die in our lifetime. It is the cockroach of the internet,” says Cal Henderson, CTO and co-founder of Slack, when I meet him for coffee at Le Méridien Hotel at London’s Piccadilly. Slack, which provides cloud collaboration software for businesses, is probably the company cited the most in the whole ‘death of email’ debate.

“If you meet someone from another company, email is blatantly the way to communicate,” he explains. But it is “weirdly formal for our time” and not ideal for people you speak to all the time, or the endless software notifications – like Twitter updates or holiday approvals – which flood our inboxes.

Slack integrates with all kinds of everyday business programs – like Salesforce, GitHub and Workday – to improve internal communication. It was only released to the public in early 2014 and has rapidly gained a reputation as the fastest growing business app. For a work tool it also generates an awful lot of enthusiasm and is a big part of the general move to consumerise work tools.

The users – who include 30,000 IBMers and a surprising number of journalists – are ever keen to show you just how brilliant it is. “There is lot of bottom up adoption,” says Henderson and as of the end of January numbers had reached five million daily active users and 1.5+ million paid users. The funding also keeps on gushing in with a total of $540M raised to date. After the last investment round in April 2016 valuation stood at $3.8 billion.

Yet as with any high growth company, many pundits believe this is not sustainable. Henderson – who was also chief software architect for consumer photo-sharing site, Flickr – says, while it is a lot easier to double in size when you’re tiny, the corporate space is also a lot smaller than the consumer one. At present, he explains 50% of users come from outside the US, despite the fact the platform is only available in English and customers can only pay on a credit card. “The plan is to launch in multiple languages later this year,” he says.

In the face of notable success, Henderson is a very down to earth, likeable Brit who has lived stateside for 12 years. He tells me he listens to audio books “at two or three times speed” on his walk to work and loves sci-fi with a particular interest in “alternate views of the future”. Like many people who code he also runs endless side projects. “We have a channel in our own Slack called games we won’t finish,” he says.

For Slack though, it is could be hard to stay to stay on the up forever. It may have started the trend for consumer-style work communication but Microsoft’s new tool, Teams might present a challenge. This reached general availability last month, sits directly in Office 365 and has already attracted 50,000 organisations possibly by default (although Microsoft already has form in this area with the acquisition of Yammer in 2012). Slack acknowledged this threat with what many see as the very misguided placement of a full page open letter of advice to Microsoft in the New York Times when the launch was announced.

“The existence of competitors is good in a number of ways,” suggests Henderson. When we started we were convincing customers to switch to a whole new category, now the rise in players in the space “validates the whole category,” he says.

So, how else is Slack developing? Well, the team is growing steadily says Henderson, with a slew of new roles mostly in Sales and customer support. Outside of the immediate need for internationalisation the company is also working hard to improve the experience for very large customers. (“We’re figuring out our capabilities with big customers,” he says.) This saw the launch of the Slack enterprise this January which aims to make communication across large organisations easier.

Naturally there are also plans to increase the capabilities of the platform itself. And like in most organisations machine learning will play a big part in delivering insight. If you’re away from work for a week, explains Henderson, the systems curates the information that was most relevant from while you were away. This is based on an aggregation of the kinds of conversations you normally have and the people you might communicate with. “If we make a reasonable job of that by a few percentage points it’s a huge,” he says.

This could also have wider implications for search functionality too. So, if you need to find out how to file expenses, for example, and there is no ‘how to’ available, the system could recommend the best employee to talk to, based on the individual who answers the most questions on this topic. Otherwise it may point you in the direction of the most active channel on the subject.

Interestingly, Henderson says they have never thought about this as a way to surface particular skills within in a company (niche startups like Uruguayan Collokia are springing up to fulfil this particular area). “It’s likely that happens we just never thought about it,” he adds.

A work tool of the scale and reach of Slack also has the potential to deliver analysis on wider company trends. However, questions like ‘is project going well’ or ‘are people on the team happy’ are “squishy” problems to solve, says Henderson. “It is something we’re interested in working towards,” he adds, although this may be in conjunction with third parties like IBM Watson.

“Consumerisation of the workplace will definitely continue,” concludes Henderson. “Doing expenses will never be a joy but [with better tools and collaboration] it could be less of a pain.”