Principality Building Society website screenshot

Principality Building Society

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.

Principality Building Society publishes 6 APIs on the APIs.io network, including ATM API, BCA API, Branch API, and 3 more. Tagged areas include Financial-Services, Banking, Building Society, Savings, and Mortgages.

Principality Building Society’s developer surface includes authentication, product news, support, and 11 more developer resources.

🌐 Visit website 📡 Source on GitHub
34.2/100 thin ▬ flat Agent 21/100 agent aware Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0
1 APIs
Financial-ServicesBankingBuilding SocietySavingsMortgagesOpen BankingOpen DataPSD2OBIEUnited KingdomWalesMutual

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0
Composite quality — 34.2/100 · thin
Contract Quality 6.9 / 21
Developer Ergonomics 5.7 / 17
Access Clarity 9.7 / 17
Operational Transparency 0.6 / 11
Contract Governance 0.5 / 10
Discoverability 5.7 / 9
Regulatory Posture 4.7 / 15
Agent readiness — 21/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 0 / 10
Documented Reversibility 6 / 6
MCP Server 0 / 12
Machine-Readable Auth 10 / 10
Idempotency 9 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 0 / 6
Agent Skills 0 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
A2A Agent Card 0 / 8
Dry-Run / Simulate Mode 4 / 4
Delegated User Identity 0 / 6
Protected Resource Metadata 0 / 5
Registration Without a Human 0 / 6
Agentic Commerce Well-Known Document 0 / 5
Regulatory Posture applies to this provider. Its tags matched the Banking & Open Finance regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.
Create-or-Update Ergonomics does not apply to this provider. The published contracts declare no write operations, and a read-only API cannot create-or-update. The facet is excluded from this provider's denominator entirely — not scored zero. A reference or data API is not deficient for being unable to upsert.
The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/principality-building-society: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 9

Individual APIs this provider publishes, each with its own machine-readable definition.

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...

Principality Building Society ATM API

Endpoint for getting ATM data

Principality Building Society BCA API

Endpoint for getting Business Current Account data

Principality Building Society Branch API

Endpoint for getting Branch data

Principality Building Society CCC API

Endpoint for getting Commercial Credit Card data

Principality Building Society PCA API

Endpoint for getting Personal Current Account data

Principality Building Society SME API

Endpoint for getting Unsecured SME Loan data

Scroll for all 9

Open Collections 1

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Open Data API

OPEN COLLECTION

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Principality Building Society Authentication

none · 0 schemes

SECURITY

Principality Building Society Domain Security

TLSv1.3 · HSTS · DNSSEC · DMARC

SECURITY

Resources

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt
LLMsTxt

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Conformance
Conformance
 ErrorCatalog
ErrorCatalog

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity
 Authentication
Authentication

Operate 2

Status, limits, changes, and where to get help

IssueTracker
IssueTracker
 Support
Support

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService
TermsOfService
 PrivacyPolicy
PrivacyPolicy

Company 4

The organization behind the API

Website
Website
 About
About
 News
News
 LinkedIn
LinkedIn

Other 1

Properties that don't map to a standard resource type

CapabilityMap
CapabilityMap

Source (apis.yml)

apis.yml Raw ↑ 
aid: principality-building-society
url: https://raw.githubusercontent.com/api-evangelist/principality-building-society/refs/heads/main/apis.yml
name: Principality Building Society
kind: company
description: 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.
deliveryModel:
  model: unknown
  open_source: unknown
  commercial: true
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  - pricing
  - repository-unlicensed
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-09-02'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
tags:
- Financial-Services
- Banking
- Building Society
- Savings
- Mortgages
- Open Banking
- Open Data
- PSD2
- OBIE
- United Kingdom
- Wales
- Mutual
tags_raw:
- Financial Services
- Banking
- Building Society
- Savings
- Mortgages
- Open Banking
- Open Data
- PSD2
- OBIE
- United Kingdom
- Wales
- Mutual
created: '2026-07-23'
modified: '2026-07-23'
specificationVersion: '0.23'
apis:
- aid: principality-building-society:obie-account-transaction-api
  name: OBIE Account & Transaction Information API (AIS - Standard, Out of Scope)
  description: 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 strong customer authentication. Represented here as the documented
    OBIE standard only - Principality offers no current or payment accounts, publishes no ASPSP developer portal, and is therefore
    OUTSIDE the scope of this Read/Write API. No Principality base URL or credentials exist; none are invented.
  humanURL: https://github.com/OpenBankingUK/read-write-api-specs
  properties:
  - type: Documentation
    url: https://github.com/OpenBankingUK/read-write-api-specs
  - type: APIReference
    url: https://openbankinguk.github.io/read-write-api-site3/
  tags:
  - Account Information
  - AIS
  - PSD2
  - FAPI
- aid: principality-building-society:obie-payment-initiation-api
  name: OBIE Payment Initiation API (PIS - Standard, Out of Scope)
  description: The OBIE Read/Write Payment Initiation (PISP) standard for initiating domestic, scheduled, standing-order,
    international and file payments. FAPI-secured with OAuth2/OIDC, mutual-TLS and PSD2 strong customer authentication. Represented
    as the documented OBIE standard only - Principality holds no payment accounts and operates no PISP endpoint, so this is
    out of scope. No Principality host is fabricated.
  humanURL: https://github.com/OpenBankingUK/read-write-api-specs
  properties:
  - type: Documentation
    url: https://github.com/OpenBankingUK/read-write-api-specs
  - type: APIReference
    url: https://openbankinguk.github.io/read-write-api-site3/
  tags:
  - Payment Initiation
  - PIS
  - PSD2
  - FAPI
- aid: principality-building-society:obie-confirmation-of-funds-api
  name: OBIE Confirmation of Funds API (CBPII - Standard, Out of Scope)
  description: 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 strong customer authentication. Represented as the
    documented OBIE standard only - Principality offers no payment accounts and provides no CBPII endpoint. No Principality
    host is invented.
  humanURL: https://github.com/OpenBankingUK/read-write-api-specs
  properties:
  - type: Documentation
    url: https://github.com/OpenBankingUK/read-write-api-specs
  - type: APIReference
    url: https://openbankinguk.github.io/read-write-api-site3/
  tags:
  - Confirmation of Funds
  - CBPII
  - PSD2
  - FAPI
- aid: principality-building-society:principality-building-society-atm-api
  name: Principality Building Society ATM API
  description: Endpoint for getting ATM data
  humanURL: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  tags:
  - ATM
  properties:
  - type: OpenAPI
    url: openapi/principality-building-society-atm-api-openapi.yml
  - type: Documentation
    url: https://openbankinguk.github.io/knowledge-base-pub/standards/open-data.html
  - type: APIReference
    url: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  - type: SourceCode
    url: https://github.com/OpenBankingUK/opendata-api-spec-compiled
- aid: principality-building-society:principality-building-society-bca-api
  name: Principality Building Society BCA API
  description: Endpoint for getting Business Current Account data
  humanURL: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  tags:
  - BCA
  properties:
  - type: OpenAPI
    url: openapi/principality-building-society-bca-api-openapi.yml
  - type: Documentation
    url: https://openbankinguk.github.io/knowledge-base-pub/standards/open-data.html
  - type: APIReference
    url: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  - type: SourceCode
    url: https://github.com/OpenBankingUK/opendata-api-spec-compiled
- aid: principality-building-society:principality-building-society-branch-api
  name: Principality Building Society Branch API
  description: Endpoint for getting Branch data
  humanURL: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  tags:
  - Branch
  properties:
  - type: OpenAPI
    url: openapi/principality-building-society-branch-api-openapi.yml
  - type: Documentation
    url: https://openbankinguk.github.io/knowledge-base-pub/standards/open-data.html
  - type: APIReference
    url: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  - type: SourceCode
    url: https://github.com/OpenBankingUK/opendata-api-spec-compiled
- aid: principality-building-society:principality-building-society-ccc-api
  name: Principality Building Society CCC API
  description: Endpoint for getting Commercial Credit Card data
  humanURL: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  tags:
  - CCC
  properties:
  - type: OpenAPI
    url: openapi/principality-building-society-ccc-api-openapi.yml
  - type: Documentation
    url: https://openbankinguk.github.io/knowledge-base-pub/standards/open-data.html
  - type: APIReference
    url: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  - type: SourceCode
    url: https://github.com/OpenBankingUK/opendata-api-spec-compiled
- aid: principality-building-society:principality-building-society-pca-api
  name: Principality Building Society PCA API
  description: Endpoint for getting Personal Current Account data
  humanURL: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  tags:
  - PCA
  properties:
  - type: OpenAPI
    url: openapi/principality-building-society-pca-api-openapi.yml
  - type: Documentation
    url: https://openbankinguk.github.io/knowledge-base-pub/standards/open-data.html
  - type: APIReference
    url: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  - type: SourceCode
    url: https://github.com/OpenBankingUK/opendata-api-spec-compiled
- aid: principality-building-society:principality-building-society-sme-api
  name: Principality Building Society SME API
  description: Endpoint for getting Unsecured SME Loan data
  humanURL: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  tags:
  - SME
  properties:
  - type: OpenAPI
    url: openapi/principality-building-society-sme-api-openapi.yml
  - type: Documentation
    url: https://openbankinguk.github.io/knowledge-base-pub/standards/open-data.html
  - type: APIReference
    url: https://openbankinguk.github.io/opendata-api-docs-pub/v2.4.0/
  - type: SourceCode
    url: https://github.com/OpenBankingUK/opendata-api-spec-compiled
common:
- type: CapabilityMap
  url: capabilities/principality-building-society-capability-edges.yml
  name: Principality Building Society Business Capability Map
- type: IssueTracker
  url: https://github.com/OpenBankingUK/opendata-api-spec-compiled/issues
- type: DomainSecurity
  url: security/principality-building-society-domain-security.yml
- type: Authentication
  url: authentication/principality-building-society-authentication.yml
- type: Conformance
  url: conformance/principality-building-society-conformance.yml
- type: ErrorCatalog
  url: errors/principality-building-society-problem-types.yml
- type: LLMsTxt
  url: llms/principality-building-society-llms.txt
- type: Website
  url: https://www.principality.co.uk/
- type: About
  url: https://www.principality.co.uk/home/about-us
- type: News
  url: https://www.principality.co.uk/home/about-us/principality-news
- type: Support
  url: https://www.principality.co.uk/home/contact-us/help-and-support
- type: TermsOfService
  url: https://www.principality.co.uk/home/terms-of-use
- type: PrivacyPolicy
  url: https://www.principality.co.uk/home/terms-of-use/privacy-and-security
- type: LinkedIn
  url: https://www.linkedin.com/company/principality-building-society/
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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