Nationwide delivers multi-cloud payments upgrade

THE CHALLENGE

Building trust in faster payments infrastructure

It’s the world’s largest building society, with members at its heart, and a cornerstone of the UK economy. Forget standard banking hours, this high-street stalwart processes around three million faster payments at peak times—bank-to-bank transfers of up to a £1m per transaction— keeping money moving instantly across the country. At its busiest, transaction volumes reach £1.5 billion in 24 hours, a disruption to this service would be no mere hiccup; it would severely impact critical national infrastructure.

On stage at a recent MongoDB London .local event, in front of an international audience, Ruud Schoonderwoerd, Nationwide’s Principal Engineer and Technical Lead, and Ketan Garde, Technical Architecture Director at Accenture UK, shared the story behind a major transformation of Nationwide’s payments architecture.

When a single outage can trigger widespread disruption, the building society’s systems must be flawless 24/7, 365 days a year. “Imagine if Nationwide stops processing faster payments—it’s going to halt the economy in some shape or form. So it's very critical that when Nationwide does payment processing, it does so in the best possible way,” said Garde. With customer confidence to maintain and regulatory pressure intensifying, Nationwide knew it needed to make its architecture optimally resilient. That imperative led the building society to partner with Accenture and Form3 to re-architect a cornerstone of the UK’s payments landscape by migrating its faster payments platform—strengthening resilience, enhancing scalability, and securing the trust that millions of members place in the bank every day.

OUR SOLUTION

Lowering risk and increasing reliability in under 8 months

Nationwide’s journey began with a bold decision to go cloud-native on one cloud provider. But for a financial institution moving billions of pounds daily, resilience meant looking beyond a single provider.

“Regulators want to know we’re not depending on any one vendor to keep services running,” said Schoonderwoerd, “Something happening to a global cloud infrastructure provider sounds unimaginable… but the unimaginable sometimes happens.”

The push for genuine multi-cloud freedom set the stage for an engineering milestone: a dual-cloud, active-active platform running simultaneously across two leading hyperscale cloud providers. “This way, we could answer the regulator question and be able to demonstrate that both platforms work at all times,” said Schoonderwoerd.

Under normal conditions, the system splits payment traffic evenly between the two. And crucially, it’s designed so that if an entire cloud were to go dark, payments would continue without missing a beat.

Nationwide and Accenture shifted their database infrastructure to MongoDB across both clouds at a pace more in line with a startup than a financial institution. “Incredibly, we went from no MongoDB code to production-ready in a relatively short timeframe,” said Garde. “And MongoDB powered this entire dual-cloud architecture—allowing us to run anywhere while maintaining performance and resilience across clouds.”

OUTCOME

Resilient and regulator-ready in multi-cloud

Through tight coordination and rigorous engineering, the team built what is widely regarded as the UK’s first dual-cloud payments platform—and potentially one of the first anywhere. And this is no off-the-shelf setup: it is a self-hosted, unified cluster spanning nine servers on one cloud provider, and nine on the other.

To ensure absolute data integrity, Nationwide’s five-node MongoDB cluster writes every transaction to both clouds simultaneously. Billions of pounds flow safely through this design every day. And if one cloud were to fail completely, the other takes over instantly, allowing payments to continue within minutes.

The environment is fully automated, too. Terraform deployments and CI/CD pipelines enable Nationwide to spin up an entire cluster, “at the click of a button, in around four hours,” said Garde, giving the bank complete control over performance, security, and scaling.

The outcome is the holy grail for members and regulators alike: higher availability, deeper resilience, and unshakable trust. It not only protects a critical piece of the UK’s financial infrastructure—it sets a new benchmark for operational excellence. Or, as Garde put it: “Possibly a world first, definitely a UK first—and all powered by MongoDB.”

Nationwide’s achievement demonstrates that with bold thinking and the right technology, even the most mission-critical financial systems can evolve at full speed—without missing a beat.