'Microsoft's new product is validation for Slack - and we have a few advantages over the tech behemoth'
Slack's founders brought the same attitude to their communication tool as they applied to their now defunct online game: "an irrational belief that whatever you're doing is definitely going to work, your idea is sound and everybody should be using your product".
This time, however, the concept worked. With more than eight million daily active users (DAU) - at last count - across at least 100 countries, the 'Searchable Log of All Conversation and Knowledge' tool has been adopted by 65pc of Fortune 100 companies.
At less than 10 years old, Slack is being integrated into a rapidly-changing workforce, impacted by catalysts including unprecedented global market trends and the ever increasing rate of technological change.
But, according to company's co-founder and chief technological officer (CTO) Cal Henderson, there's also an internal pressure for change, as within the next year, some 50pc of the workforce will be millennials.
"This new workforce brings with it a certain set of expectations around the tools they use, how they communicate, not to mention the work-life balance and how they interact with work.
"The way people think about jobs and careers and work has just changed significantly over the last decade," he said.
"Humans are difficult, messy creatures - they are difficult to get along with. Anything that can help the productivity of the team is going to be hugely beneficial to companies in the future."
Slack has been described as the 'email-killing' messaging service, encouraging further collaboration and more productivity between teams across a range of industries through an internal hub, which sorts incoming notifications into easy-to-use channels.
But, for England-born Henderson, who previously built and led the engineering team at Flickr, he doesn't believe that email will ever die. "It's kind of like the cockroach of the internet, nobody likes it but it's impossible to eradicate.
"The mail will be impossible to dislodge but what we will see is more and more email use cases moving towards something that's more suitable for that particular mechanism.
"The email has become the default dumping ground for every bit of information that needs to be pushed to you, but the format doesn't really work very well, it's not built for it. And it all goes into one undifferentiated pile."
Tech companies were unsurprisingly the first to see the benefits of using Slack in their day-to-day work, with media organisations following close behind; Fox News uses to tool to communicate between their helicopters in the sky and their news rooms on the ground for real-time information.
Now, however, 60pc of users are in non-technical roles - whether that be marketing, sales, HR, finance etc - with more than 70,000 teams paying for the service, from small businesses through to those Fortune 100 firms.
"Increasingly every industry has knowledge workers and would benefit from increased team collaboration.
"We charge on a 'per seat' basis, so if you have five users, you pay for five seats," said Henderson.
Some well-known Irish firms, including Stripe, Intercom and Paddy Power, are on their client list, and the company's EMEA HQ - and second-biggest office - is based at Hatch Street in Dublin.
"We're trying to grow this office at a fast but sensible rate. Ireland has been a good choice for us - well-positioned - we can attract talent from all across Europe here. We're constantly recruiting," he said.
CEO Stewart Butterfield's assertion at the official opening of the new headquarters in January 2017 that the site's headcount would grow to 180 by year-end was perhaps overly ambitious - the Dublin workforce is at around 100 employees now.
But Henderson maintains that true validation for the type of product that Slack was providing came in the form of Microsoft's launch of 'Teams' over the summer months.
"It is very validating for the world's biggest enterprise company to come along and make a product in the same space.
"It says that we're not insane, this is a product category that the majority of knowledge workers will be using a channel-based communication method within the next five to 10 years.
"This really is a new thing that people are working towards."
Nonetheless, with great power comes great responsibility, and Henderson acknowledges the demands required by customers if they are asking them to run their business on Slack.
In June, the platform - which ordinarily boasts 100pc uptime - was disrupted for a number of hours before the issue was isolated and resolved.
Is this another reason, like cash, why email will never die?
"Slack is more like a utility, it's more like having power or internet. That is a big responsibility for us for sure and it is a big focus of our investment at the moment making sure that reliability is up the level that the customers require of us," said Henderson.
"One hundred per cent availability is something that's impossible to achieve but we'll continue to aim for it, and invest in that forever."
"There are at least 600 million total knowledge workers across the globe and at eight million DAU now, we've got huge potential there.
"It's not that the audience are using something like Slack, but they just may not be aware that this is a category that they can use.
"We have a few advantages over Microsoft, a big behemoth with a massive sales team and a lot more experience in enterprise software than we do.
"We can partner with everyone that makes enterprise software because we are not in direct competition with them.
"We also only make exactly one product and the company is entirely focused on making that product as great as possible."