NatWest Boxed completes zero-downtime platform migration
Embedded finance lets brands embed banking services directly into their customer journeys, but the back-end must remain secure and reliable. NatWest Boxed, the banking-as-a-service arm of NatWest Group, is building a platform that lets UK retailers and clubs offer savings accounts, unsecured loans and point-of-sale credit without constructing their own bank.
Building a next-generation platform
NatWest Boxed was established around 2022, initially partnering with a European technology provider. The bank kept control of its core ledger while the partner ran the orchestration layer that linked front-end experiences to banking functions.
Within two years the venture shifted to an entirely internal solution. Engineers migrated the live service to a new stack without shutting down existing products, a process Asif Siddiqui, Director of Engineering, Banking as a Service, described as a “large-scale migration carried out while the business was already live.”
To limit risk, the team introduced a phased blueprint that split functionality into micro-domains such as identity verification, account onboarding and customer management. Each domain could be owned by a dedicated squad, allowing changes without a full system outage.
An orchestration layer was added to route requests between the legacy stack and the new micro-services. Front-end channels and APIs were gradually repointed, so individual features moved over several months rather than all at once.
Because banking is heavily regulated, the migration required a synchronization system that kept customer records aligned across both environments. The dual-system approach ensured no data loss and allowed the cut-over to occur with zero customer downtime.
“We cannot afford to lose a single data point or trigger a huge amount of downtime while we migrate,” Asif Siddiqui explained, noting that the real-time sync and orchestration were essential to meet regulatory expectations.
Engineering for speed and resilience
The architecture follows cloud-native, API-first principles and adopts continuous integration and continuous deployment. Small code changes are merged and tested frequently, and approved updates are released automatically, reducing the chance of large-scale failures.
Partnerships with The AA, Saga and Sainsbury’s demonstrate the need for configurable solutions. Each brand can customize visual branding, integrate its own authentication system and link financial products to loyalty programmes, while the underlying banking infrastructure remains consistent.
The platform is developing point-of-sale lending with The AA, allowing members to access credit during service bookings without leaving the brand’s app.
NatWest Boxed’s proposition for Saga, for example, required a customer journey designed around people over 50, highlighting the importance of adaptable and configurable embedded finance solutions that cater to diverse customer segments.
