Framework 01 — Open Banking
v1.0 RFC · Open Standard · CC BY 4.0
A privacy-by-design API protocol that replaces all-access bank data extraction with:
The Problem
Today's open banking APIs — introduced under frameworks like PSD2 and the Open Banking Standard — grant authorized third parties full read access to a customer's transaction history, balance data, and behavioral signals. The consent layer is present. The data minimization layer is not.
The data extracted routinely exceeds what any individual use case requires. A lender verifying affordability doesn't need six months of transaction history. A landlord checking rent eligibility doesn't need investment account details. Yet the protocol grants access to all of it, and relies on downstream parties to self-limit their use.
This is structural overreach — not a compliance gap, but an architectural one. The protocol layer never asked: what is the minimum data needed to answer this specific question? LDBP asks that question. And builds the answer into the API.
The Protocol
LDBP introduces a scoped Boolean verification endpoint to the open banking stack. Rather
than returning raw financial data, the /balance/verify endpoint accepts
a verification intent and returns only what the use case requires: a pass/fail.
A lender doesn't need your balance. They need to know if it's enough. LDBP encodes that distinction at the protocol level — making privacy-by-design structurally enforced, not policy-dependent. The data never leaves the institution. Only the answer does.
POST /balance/verify — response
{
"verified": true,
"intent_id": "ldbp_abc123",
"expires_at": "2026-12-31T23:59:59Z"
}Built For
01
Verify affordability without extracting transaction history. LDBP lets lenders confirm a threshold is met — not browse a balance sheet.
02
Enable landlords and utilities to confirm financial eligibility with a single Boolean — no income details, no account data, no behavioral trail.
03
Give AI financial agents the minimum signal required to act — constraining data scope at the protocol layer, not through model-level guardrails.
04
Demonstrate data minimization at the API layer — a verifiable, auditable architecture for GDPR, PSD2, and emerging open finance regulation.
Artifacts
Full specification and design rationale
Machine-readable API specification, GitHub
Source repository and README
How to certify LDBP compliance
All artifacts published under CC BY 4.0.
Cite as: Belarmino, M.A. (2026). Least-Data Banking Protocol v1.0 RFC. BelarminoAdvisory.com/frameworks/ldbp
Get Involved
If you're a fintech, bank, or platform evaluating LDBP for your open banking stack, reach out to discuss implementation support and conformance review.
If you work in financial regulation or standards bodies and want to discuss LDBP's design rationale, Mary Ann is available for technical briefings.
If you're a researcher, protocol designer, or standards contributor who wants to engage with the RFC, open a discussion on GitHub or reach out directly.