Tucked away on a quiet street amid the canals and old buildings of central Amsterdam, the head offices of Adyen reflect its reputation as one of the tech industry's biggest behind-the-scenes companies.
With a valuation of $2.3 billion, and clients including Facebook to Uber, you might be surprised that you haven't heard of Adyen.
"The culture which we have has contributed to our success," Pieter Van der Does, co-founder and chief executive of Adyen tells CNBC.
Van der Does, looking relaxed after returning from a vacation where he's been windsurfing, explains that unlike consumer-facing payment apps like Apple Pay, Adyen works on the back-end and is a business-to-business product.
It's not well known among consumers and Van der Does likes it that way.
"You can be screaming and proud but that role doesn't suit us as it's our merchants doing the work and we are making sure that consumers over the world can pay any way they want," Van der Does tells CNBC, sipping on a cappuccino made by his company's barista.
"That role means that we don't want a relationship with a consumer and that role means that we sit behind the merchant in an invisible way."
Adyen is not young. The company was founded in 2006 and has been quietly growing at a rapid pace. Last year, revenues almost doubled year-on-year to $350 million and the company has been profitable since 2011, a feature many of the world's biggest start-ups would love to boast about.
So what does the company do?
It began by helping web companies such as Facebook collect payments and then moved into mobile as firms such as Uber were on the rise. Adyen then released software that runs on point-of-sale terminals to help bricks-and-mortar stores.
Around the world, 4,500 businesses use Adyen's solutions. It's not a large number but the companies it counts as its clients are huge.
"Our focus is managing the rapid growth that we have," Van der Does explained, outlining the start-up's priorities.
While Adyen has largely remained under the radar for consumers, it is well-known among investors, particularly Silicon Valley's elite. Adyen recently snagged a $2.3 billion valuation after an investment from Iconiq Capital - the little-known wealth management firm that manages investments for the likes of Facebook boss Mark Zuckerberg, LinkedIn CEO Reid Hoffman and Twitter CEO Jack Dorsey. Adyen is part of the growing group of "unicorns" - or start-ups valued over $1 billion.
At the end of 2014, Adyen raised $250 million from General Atlantic with participation from existing investor Index Ventures. Among the other investors are Silicon Valley's Felicis Ventures and Temasek Holdings.
But Adyen does not need cash. It's profitable. Still, Van der Does explained that the company is very careful on its spending, as he pointed at the Ikea lampshade in his office.
It's a very European attitude the founder takes versus the often high "burn rates" shown by U.S. start-ups. Earlier this year, top venture capitalist Bill Gurley sounded the alarm on the "unique circumstances" start-up CEOs find themselves in caused by "the pressures of lofty paper valuations, massive burn rates (and the subsequent need for more cash), and unprecedented low levels of IPOs and M&A".
Gurley added that companies should start focusing on being profitable. Often start-ups will eschew profitability in exchange for scaling and growth. But Van der Does said that while this is important, founders need to have a plan to become profitable.
"There is nothing wrong with being lossmaking and nothing wrong with raising a round, and if one round is lower than another that can happen, but what you shouldn't forget is the day you are profitable it changes something for your company," Van der Does told CNBC.
"It's nice you don't have to raise funds, that you can time an IPO (initial public offering) yourself, it empties out a lot of work on your agenda, and it's nice Adyen can focus on building a strong company."
Also, Van der Does said that the company only issues common stock, meaning no investor has any preferences, a way of "keeping it simple".
Adyen is not alone in what is becoming a highly competitive payments space. Swedish start-up Klarna and U.S. firm Stripe are both competitors. And it's not just start-ups that could be potential challengers.
"The online and mobile payments is becoming increasingly competitive and attracting interest from players across the technology industry. Companies like Apple, Google, Facebook and Samsung are ramping up their payments activities to potentially target users across in-store, online, mobile and in-app use cases. This threatens to disrupt even established players," Ruomeng Wang, analyst at IHS, told CNBC by email.
Now nearly 10 years old, Adyen is deciding what the future holds. At some point, its investors will want their returns.
With capital readily available, start-ups have opted to stay private for longer. Uber's Chief Executive Travis Kalanick recently told CNBC he is going to "make sure it (a public flotation) happens as late as possible". Adyen's boss is relaxed about the situation and said that the company is not planning for an initial public offering yet.
"Today is not the right timing. If you run a loss-making company, you cannot forever keep raising, and you look at that question in a different way. For us it would be a different way of how we deal with shareholders. It's not a fundraising mechanism which we need to start to be able to continue our business. There is no pressure there," Van der Does told CNBC.