By the time he was 15 he was making up to $1000 a week selling broken phones he had fixed on eBay, and in 2015 he spent the summer holidays learning how to create mobile applications.
Over the next few years, he sold more than 100 apps that would made a total of US$360,000 ($553,000) in revenue through a website called flippa.com.
But it wasn't until early 2017 that the teens joined forces and went into business together, launching their agency, Kickspan.
Today they offer a wide range of services to more than 12,000 clients, including website and mobile app development, Facebook advertising and Instagram management, graphic design, data collection and digital consulting – and the business is now generating "over six figures a month" and is valued at more than $5 million.
"When we met in Year 7 we didn't really like each other at the time, so it's pretty ironic that we later ended up as best friends and went into business together," Tsiouklas, now 19, told news.com.au.
He said the pair would meet up in the school library and spend their lunchtimes working for clients.
But Gokoglu said they had faced some tough times at school despite their success.
"People used to take the p**s out of us and say we were going nowhere – I was mocked in IT class which was surprising because we had breakthrough after breakthrough, but nobody believed in us," he said.
"People just laughed which was annoying, but it pushed me (to succeed).
"It helped motivate me – we always believed in ourselves and that self-belief helped us push through struggles in life and in business. We knew 100 per cent we were going to succeed and nothing could stop us."
They also initially struggled to prove themselves due to their youth, although ultimately, clients learnt to focus on their results and not their date of birth.
"At the end of the day, especially in the digital age, older people want to work with younger people because they understand tech better – they grew up with social media and understand what is trending and what works, and a lot of people actually reached out to us purely because we were young," Mr Tsiouklas said.
"There is value in being young and it shows through our results and credibility."
Tsiouklas is now studying business at Monash University and Gokoglu plans to study IT at Swinburne next year, although their primary focus remains on the business.
And despite their phenomenal success, they said they were less concerned with financial rewards than professional ones.
"To be honest I don't do it for financial gain – seeing those results makes me proud, but what I really love is innovating every day and coming up with new things people love," Gokoglu said.
"Seeing people – including celebrities – using our products gives me more of a buzz than seeing money," Tsiouklas said.
Some of those celebrities include popular musicians Supreme Patty, XXXTENTACION and YBN Nahmir, who helped launch the Clout the Game app in 2018, which reached the top 10 in the Apple App Store in the US after reaching 250,000 active users in just 48 hours.
At 17, Tsiouklas also built an app for celebrity Blac Chyna, who was collaborating with Body Blendz, which promoted those products in the form of a mini-game.
And about six months ago, the pair purchased the domain name TikToks.com for $2000 after predicting TikTok would become the next big social media platform.
They've recently been offered US$145,000 (AU$209,947) to buy it, but they plan to hold it and launch the world's first TikTok growth service.
Their next major project is Apps4Brands, a service which will allow any business or influencer to create an application of their own for $99 a month, which the business partners believe will soon become an essential part of every business in the future.
Tsiouklas said his generation – Gen Z – was only just starting to make waves as they came of age – but said their natural tech know-how would change the world.
"Get ready for the Gen Z business revolution, because it's definitely coming," he said.
