Report: a group of central banks developed 33 API functionalities to test 30+ CBDC online, offline, and in-store use cases, via QR codes, phones, and more
An API layer could facilitate a wide range of central bank digital currency payment scenarios, a Bank for International Settlements and Bank of England experiment has shown.
Context & Ripple Effects
CBDC work has been moving from paper to plumbing for three years. In 2020, seven central banks including the Fed published core design principles, and Mastercard shipped a tool for issuers to simulate digital currency issuance before committing — testing without live rails. The BIS–Bank of England experiment is the next step: instead of each jurisdiction designing its own interfaces, a shared layer of 33 API functionalities lets one codebase exercise 30+ retail scenarios, from QR-code in-store taps to offline phone payments.
It matters because the [[a:982910|ECB already had to recruit Amazon, Nexi, Worldline and others just to prototype digital euro user interfaces]] — evidence that interface work is where CBDC projects stall. The BoE has also signaled a [[entity/bank-of-england|preference for centralized database architecture over blockchain for the digital pound]], so an API abstraction layer fits how it intends to build.
First-order effects
- Participating central banks gain a reusable test harness: the same 33 functionalities cover online checkout, offline transfer, and in-store QR payments, cutting the bespoke engineering each national pilot would otherwise need.
- Payment technology vendors like those on the ECB's digital euro shortlist now have a reference API surface to build wallets and merchant terminals against, rather than guessing at each central bank's requirements.
Second-order effects
- Private players such as Mastercard, whose business began with selling central banks a standalone simulator, face pressure to conform their tooling to this emerging common API layer or lose relevance as the de facto test environment.
- If offline and in-store use cases pass at scale, retail pilots like the RBI's nine-bank CBDC trial gain a template for extending beyond select-location apps into everyday merchant acceptance.
Third-order effects
- A shared API specification positions the BIS as a standards body for retail CBDC — the same convening role it played when French, Swiss, and Singaporean authorities tested cross-border wholesale settlement with DeFi in the Project-related experiments — shifting industry structure toward interoperable national currencies rather than isolated domestic silos.
- If the pattern holds, the competitive question for card networks moves from issuing tools to whether central bank rails absorb everyday in-store volume that today routes through private card schemes — a genuine open question, since no country in this corpus has yet committed to full-scale retail deployment.
The trend: CBDC development is shifting from national design principles toward standardized, API-driven interoperability testing coordinated through the BIS.