Buy In, Break Out How AI transformed OnBuy from underdog to market leader - and why the UK tech scene is just getting started.

"We're no longer dabbling; we're scaling with AI." It's not just a shift in strategy, but in mindset - and for Cas Paton, CEO and founder of rapidly growing UK marketplace OnBuy, that change has been transformative. In just twelve months, what was once an experiment has become the core engine behind the business's explosive momentum.

"It would have to be the deep integration of AI into our operations," he says of what's working in 2025 that wasn't just a year ago. "In 2024 we were still experimenting, using AI for isolated tasks and basic automation, but a year later AI is fully embedded into our workflows, from fraud detection to product categorisation."

A standout example is their auto categorisation system, according to Paton, which uses an AI model and vector database technology to accurately categorise products over 6,600 categories. "In just a few weeks we've recategorised over 20 million products - a task that would have taken a team of five over 20 years at an estimated cost to the business of over £4m. Accuracy is now over 93%, making many products more discoverable, which has unlocked more than £4m in GMV for our sellers."

The results are staggering, but Paton's clarity is what cuts through: AI is no longer a shiny object or a side project - it's the architecture of the company itself. They have shifted their approach. AI is no longer an experiment - it's becoming a core part of their growth strategy. "That shift is allowing us to grow faster, operate more efficiently and deliver more value to our sellers and customers than ever before," he adds.

This transformation in thinking - from add-on to absolute - hasn't merely sped up progress; it has reshaped the very foundations of how companies operate. "We've stopped treating AI as an option," Paton says, reflecting on the most powerful change within the company. "Initially, we used it sparingly for things like generating formulas or speeding up research. Once we embedded AI into our core operations, everything changed, from fraud prevention to product categorisation." The impact has been economic as much as operational. "The implementation of AI has transformed OnBuy from losing £1m per month to a business delivering tens of millions of pounds of gross profit per year."

It's a powerful example of what happens when technology becomes truly structural. "By removing friction for sellers and freeing up our team to focus on higher-value work, AI has become a growth engine, rather than a tool."

But Paton's success with OnBuy is not just a story of tech adoption. It's also a challenge to conventional wisdom in start-up culture - and a rejection of the polished, rigid paths so often held up as gospel. "I used to think that building a successful tech company meant playing by the rules set by others - get the credentials, chase the VC playbook, perfect the product before launch, and follow the crowd," he reflects. "I thought success hinged on ticking all the boxes and having everything polished and proven before going to market." Instead, OnBuy took a different route: imperfect, bold, and unapologetically independent. "What I've learned is that speed, adaptability and listening to your customers matter far more than perfection," he says. "At OnBuy, we launched with a clear vision, but an imperfect product and we iterated - fast! That agility is what helped us become one of Europe's fastest-growing businesses."

The insight is sharp: "Perfection is a moving target. Progress is what builds momentum. Sometimes the most powerful path is the one you create by challenging the rules, not following them." That instinct to challenge the status quo didn't stop with product decisions. It informed the very foundation of OnBuy itself - a UK-born e-commerce marketplace launched in the long shadow of American behemoths like Amazon.

"When I started OnBuy, I was told that it wasn't viable to introduce a UK marketplace in the shadow of global competition," Paton says. "Now, as one of Europe's fastest-growing businesses I think it's safe to say we've proven otherwise." Today, he sees something shifting - not just in OnBuy's growth, but in the broader sentiment among consumers. "Right now, one of the most underrated edges a UK founder has is timing," he says. "We're seeing a real shift in public opinion away from global tech giants. Consumers are actively seeking alternatives, especially those that are home grown and value driven."

It's a rare moment, he argues, where the door is ajar - not just for OnBuy, but for UK founders at large. "With US dominance visibly waning, the door has never been left open for UK founders to challenge the status quo and reshape the tech and retail landscape." But Paton's ambitions don't stop at taking market share. His vision reaches toward a more global - and more equitable - ecosystem.

"My vision is for a UK where start-ups aren't just surviving, they're leading," he says. "We have the talent and infrastructure to become a global benchmark for innovation, resilience and ethical entrepreneurship." He sees positive signals - including from policymakers. "The government's recent Cyber Growth Action Plan is a strong signal that we're serious about leading in high impact sectors like AI and cybersecurity, but we need to think bigger."

For him, "thinking bigger" means removing the handbrakes on scale. "Startups need to be able to scale globally from day one. We need funding to be frictionless and regulation that moves at the speed of innovation." But Paton is no libertarian. His vision of regulation is not about absence, but agility. "Agile regulation isn't about less oversight; it's about smarter oversight, and it's how we unlock the next wave of unicorns." And he believes OnBuy itself is evidence that it's possible - even powerful - to build from the UK, for the world.

"At OnBuy, we've shown that a UK-born marketplace can take on global giants, and that should be the blueprint, not the exception," he says. "We need to build an ecosystem that rewards bold thinking, supports diverse founders and champions ethical innovation."

If the foundations are laid correctly, Paton argues, the UK's position in global tech could be more than relevant - it could be definitive. "If we do, the UK won't just be a great place to start a business," he says. "It will be the best place to build the future."