# Principality Building Society

**Canonical:** https://apis.io/providers/principality-building-society/  
**Website:** https://www.principality.co.uk/  
**APIs profiled:** 4

Principality Building Society is the largest building society in Wales and the sixth largest in the United Kingdom, founded in 1860 and headquartered in Cardiff. It is a mutual, owned by and run for the benefit of its members rather than shareholders, holding total assets of more than £11 billion and operating around 71 branches and agencies alongside internet and telephone channels. Its product range is deliberately narrow - savings, residential mortgages and investments, plus a commercial lending division - and it does NOT offer current or payment accounts. Principality is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the PRA, and is a member of the Building Societies Association. It is NOT one of the nine CMA9 banks mandated to deliver UK Open Banking, and because it holds no payment accounts it falls outside the scope of the PSD2 / OBIE Read/Write (AIS, PIS, CBPII) standard. As of this profile Principality publishes no public developer portal and no confirmed OBIE Open Data API endpoint; the Open Banking API family below is represented as the shared Open Banking Implementation Entity (OBIE) standard for reference only, not as a Principality-operated contract.

## Kin Score — 25.8 / 100 (emerging)

Scored 2026-08-17 under rubric 0.11.0. Trend: flat (+0.0 from 25.8).

| Facet | Score |
|---|---|
| Discoverability | 72.2 |
| Contract Quality | 39.6 |
| Governance | 3.1 |
| Operational Transparency | 0.0 |
| Developer Ergonomics | 15.2 |
| Commercial Clarity | 21.1 |

Regulatory layer — **Banking & Open Finance**: 31.6 (matched via tags).

## Agent readiness — 28.8 (agent-aware)

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

## APIs (4)

- **OBIE Open Data API (Shared Standard - Unverified for Principality)** — The UK Open Banking Implementation Entity (OBIE) Open Data API standard - public, unauthenticated reference data covering Branches, ATMs, Personal Current Accounts, Business Cur...
- **OBIE Account & Transaction Information API (AIS - Standard, Out of Scope)** — The OBIE Read/Write Account and Transaction Information (AISP) standard for reading account, balance and transaction data. FAPI-secured with OAuth2/OIDC, mutual-TLS and PSD2 str...
- **OBIE Payment Initiation API (PIS - Standard, Out of Scope)** — The OBIE Read/Write Payment Initiation (PISP) standard for initiating domestic, scheduled, standing-order, international and file payments. FAPI-secured with OAuth2/OIDC, mutual...
- **OBIE Confirmation of Funds API (CBPII - Standard, Out of Scope)** — The OBIE Read/Write Confirmation of Funds (CBPII) standard for confirming whether funds are available on a payment account. FAPI-secured with OAuth2/OIDC, mutual-TLS and PSD2 st...

## Security (2)

- **Principality Building Society Authentication** — none · 0 schemes
- **Principality Building Society Domain Security** — TLSv1.3 · HSTS · DNSSEC · DMARC

## Tags

Financial Services, Banking, Building Society, Savings, Mortgages, Open Banking, Open Data, PSD2, OBIE, United Kingdom, Wales, Mutual

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