Build It Your Way: How Zeller's Open SDK Is Changing What Developers Can Do With Payments

Building a custom payment integration has never been easier thanks to Zeller Developer Suite. Read on to learn how one operator built a custom POS system from the ground up, then integrated it seamlessly with Zeller Terminal.

When Sebastian Alarcon Pinto, an ex-computer scientist and founder of Urku, a Melbourne-based chocolate company, went looking for a point-of-sale solution, he didn't find what he needed on any shelf. So he built it himself. He coded a custom POS system complete with a loyalty program and a kitchen display system. Using Zeller Developer Suite he was then able to integrate Zeller Terminal directly into his custom-built POS, enabling it to quickly push transactions directly to the payment terminal and offer his customers QR code receipts. A seamless integration that allowed him to complete the build in record time.

Removing the barrier to payment integration

Until now, developers building payment integrations have either been restricted by access or deterred by complex global platforms with limited local support. Providers that orient their architecture toward their own hardware ecosystem limits what customisation is possible. And larger global providers often come with much deeper complexity both in terms of pricing and integration, which is especially frustrating for developers who only need a subset of its capabilities.

Zeller Developer Suite solves this. It gives teams full SDK access from the outset, across React, React Native and Windows .NET, giving them the ability to integrate into their existing Android, iOS and Windows based applications. There are no restricted tiers to unlock, and no ceiling on what a developer can inspect or build.

“Normally you're just given limited access to the connections — that's it. With Zeller’s Developer Suite, I could actually go in and read the documentation, understand the transactions, understand the logic. I knew that a developer had genuinely put time into it.”

Sebastien Alarcon Pinto

Documentation that developers actually use

Access is only half the equation. The other half is documentation clear enough to use. This is where many payment SDKs fall short. Developers building on Zeller's SDK consistently point to the documentation as a differentiator. The logic of the transaction flow is explained and the first integration milestone is achievable quickly, without requiring a support escalation or a call with an account manager.

“The very first thing we coded was the full connection, and the handshake worked straight away. I couldn't believe it.”

Sebastien Alarcon Pinto

Speed to integration

For Sebastian, building a fully custom POS with loyalty programme, kitchen display system, automatic weekend service charging, and customer database took just six weeks. In the first week alone, he shipped 32 deployments. The SDK did what the documentation said it would do, consistently, from the first connection onwards. “It's just been easy — I don't have to worry about the connections, and I've never had a failed transaction,” says Sebastian.

What openness enables

The practical value of Zeller Developer Suite isn't just speed — it's the range of things a developer can build with it. In Sebastian’s case, that meant a two-stage transaction status system — distinguishing between payment confirmed and settlement verified — that he later evolved into a kitchen display system showing real-time order status to baristas. It also meant automatic weekend surcharging that replaced a manual process of re-entering all product prices every Friday. But perhaps what resonated most for Sebastian, was finding a platform that approached payments the same way he approaches his service: from the customer experience backwards. "When I saw that Zeller offered QR code receipts with a download option right on your phone, that told me that they work the same way I work: from the customer experience towards the functionality, not from a revenue idea backwards. That's what I really liked."

Built for how you do business

Beyond the technical architecture, Zeller Developer Suite offers something that global platforms by definition cannot: infrastructure designed around Australian and UK business conditions from the ground up. Weekend service charge rules, local award rates and banking norms, and the specific compliance requirements that affect local merchants are built into Zeller's platform rather than retrofitted. For a developer building a POS or payment integration, it means the platform's defaults are closer to what their local customers actually need.

What it means to build on Zeller

For developers evaluating payment SDK options in Australia or the UK, Zeller Developer Suite offers full access, clear documentation, fast integration, and a platform designed for the market where their clients actually operate. Zeller's Developer Suite is available now for Terminal and Online integrations, with Tap to Pay and eCommerce support coming soon. The SDK supports React, React Native, Android, iOS, and Windows .NET.