Former bank executives Alex Leong, 33, and Andrew Wong, 35, did not have clear ideas about what they wanted to do when they started their first company - but went charging ahead any way.

Their five-year journey with their start-up, Rainmaker Labs, saw not only the crash of their first app within a year, but also a change in focus to take advantage of the digital economy by targeting businesses instead of consumers.

The duo met six years ago when they were both working in the finance industry.

A year later, they decided to start their own app development company, after the global banking landscape changed following the collapse of Lehman Brothers in 2008.

"Banking was no longer a rosy prospect. We were very highly paid professionals, but what were we adding to society?" said Mr Leong.

"We saw a very large trend, five years ago, when the mobile (sector) was picking up - (a new) iPhone had just come out, and that was the future. So, we decided to catch that train early."

Rainmaker Labs was set up in 2011, the same time the digital economy was booming as a full-fledged industry. The company has since evolved from being a mobile app development firm for businesses to a maker of enterprise software, with a focus on mobile apps.

It made more than $2.5 million in revenue last year - a far cry from its initial revenue of $200,000 in its second year, following the ups and downs of its first app. The company started with a team of five and now has around 50 staff spread across the region, including Vietnam, Thailand and Australia.

Rainmaker Labs' first app, ShopGuru, launched in May 2013, was an ambitious undertaking. It was a customer loyalty app which would automatically be opened on a customer's smartphone when he walked into a shop, via ultrasound sensors placed at the entrance.

The customer then earned points automatically by browsing and purchasing products.

But Mr Leong and Mr Wong severely underestimated the operating costs and demands of such an app, along with problems in integrating hardware and software seamlessly. By the end of 2013, the app folded and the founders went back to the drawing board.

At their lowest point, the company's founders were down to $6,000 in their company account.

Said Mr Wong: "We took up small app development jobs to keep us going. But over time, we took more of such jobs and it became the new normal for us. And so we did that for a few years."

They have since developed apps for corporate clients in the tourism, automotive, gaming and manufacturing industries.