The State of UK Payments APIs

About this paper

Britain pointed a mandate at payments, not just data — a conformance regime and real account-to-account write surfaces — and produced the densest cluster of API-native payment companies in the world relative to its size. This report scores thirty-two of them the way an agent would read them, and finds the deepest open-banking contracts anywhere sitting on top of a paradox.

The UK is the FAPI/mTLS heartland, and that security spine is nearly invisible in the specs: the payment-initiation leaders hide it behind a plain bearer token, and only one provider in thirty-two surfaces it. The full report maps the account-to-account frontier, why the sector bunches below Exemplar, why the marquee brand names do not lead, and the opening the mandate left wide open — re-surfacing the consent and security layer an agent needs to see.

What's inside

1. Executive summary — a mandate pointed at payments, and the invisible spine
2. The state of the sector — a mandate pointed at payments
3. The resource taxonomy — the A2A frontier the rest of the world lacks
4. The composite Kin Score — and why it's the foundation
5. Agent-readiness — deep contracts, thin vendor infrastructure
6. The blueprint — what the leaders satisfied, and what nobody has
7. Standards and artifacts — why this matters for the agentic turn
8. Security, auth, scopes, and consent — the invisible spine
9. Provider-by-provider intelligence — the leaders and the frontier
10. The investable thesis — the mandate did the hard part

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