# Yorkshire Building Society

**Canonical:** https://apis.io/providers/yorkshire-building-society/  
**Website:** https://www.ybs.co.uk/  
**APIs profiled:** 6

Yorkshire Building Society (YBS) is a UK mutual building society founded in 1864 and headquartered in Bradford, West Yorkshire. As a member-owned mutual rather than a shareholder-owned bank, it is owned by and run for the benefit of its savers and borrowers, with more than three million customers and around £66 billion in assets across the YBS Group, which trades under the Yorkshire Building Society, Chelsea Building Society (CBS), Norwich & Peterborough and Accord Mortgages brands. YBS is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the PRA as an FCA-authorised ASPSP. Although it is not one of the CMA9 banks mandated to build Open Banking, YBS is a voluntary participant in the UK Open Banking / PSD2 ecosystem and operates a public developer portal at developers.ybs.co.uk that documents its OBIE Read/Write API family - Account Information (AIS), Payment Initiation (PIS), Confirmation of Funds (CBPII), Event Subscriptions, Dynamic Client Registration, and token issuance - conformant to the Open Banking Implementation Entity (OBIE) Read/Write Data API Standard v3.1.2. Access to the production and sandbox surfaces (ob-ybs.api.ybs.co.uk / ob-che.api.ybs.co.uk and the matching sandbox hosts) is secured with FAPI-grade OAuth2/OIDC, PSD2 strong customer authentication, mutual-TLS transport authentication and PS256-signed JWTs, and is available to FCA-authorised third-party providers holding eIDAS/OBIE certificates.

## Kin Score — 48.4 / 100 (developing)

Scored 2026-08-20 under rubric 0.12.0. Trend: flat (+0.0 from 48.4).

| Facet | Score |
|---|---|
| Discoverability | 92.6 |
| Contract Quality | 57.9 |
| Governance | 30.3 |
| Contract Governance | 30.3 |
| Operational Transparency | 7.9 |
| Developer Ergonomics | 56.5 |
| Commercial Clarity | 21.1 |
| Access Clarity | 21.1 |

Regulatory layer — **Banking & Open Finance**: 60.8 (matched via tags).

## Agent readiness — 41.7 (agent-ready)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | derived |
| Reversibility Documented | no |
| MCP Server | no |
| Auth Clarity | yes |
| Idempotency | documented |
| Error Semantics | documented |
| OpenAPI Examples | no |
| Rate Limit Signal | verified |
| Event Surface Described | derived |
| Agent Skills | derived |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |

## APIs (6)

- **Yorkshire Building Society Account Information API** — OBIE Read/Write Account and Transaction Information (AISP) API v3.1.2 - lets FCA-authorised account information service providers retrieve account, balance, transaction, benefic...
- **Yorkshire Building Society Payment Initiation API** — OBIE Read/Write Payment Initiation (PISP) API v3.1.2 - lets FCA-authorised payment initiation service providers set up domestic single, scheduled, standing-order and file paymen...
- **Yorkshire Building Society Confirmation of Funds API** — OBIE Read/Write Confirmation of Funds (CBPII) API v3.1.2 - lets FCA-authorised card-based payment instrument issuers set up a funds confirmation consent and confirm whether a sp...
- **Yorkshire Building Society Event Subscriptions API** — OBIE Read/Write Event Subscriptions API v3.1.2 - lets an onboarded TPP create, read and delete event subscriptions so it can receive aggregated-polling and real-time event notif...
- **Yorkshire Building Society Dynamic Client Registration API** — OBIE Dynamic Client Registration (DCR) API v3.1 - lets an FCA-authorised TPP present its OBIE/eIDAS software statement and register a client application with the YBS and Chelsea...
- **Yorkshire Building Society Generate Access Token API** — OBIE token endpoint (Generate Access Token API v3.1.0) - the OAuth2/OIDC token endpoint used by onboarded TPPs to exchange authorization codes and client credentials for access ...

## MCP servers (1)

- **Yorkshire Building Society MCP Server**

## Agentic access (1)

- **Yorkshire Building Society Agentic Access** — 78 operations · 23 acting

## Security (2)

- **Yorkshire Building Society Authentication** — oauth2/mutualTLS · 3 schemes
- **Yorkshire Building Society Domain Security** — TLSv1.3 · HSTS · DMARC

## Tags

Financial-Services, Banking, Building Society, Open Banking, PSD2, OBIE, FAPI, United Kingdom, Payments, Account Information, Fintech

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/yorkshire-building-society/). Scores are computed from the provider's own public artifacts under a published rubric.