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 9 API contracts indexed on the APIs.io network, including ATM API, BCA API, Branch API, and 6 more. Tagged areas include Financial Services, Banking, Building Society, Savings, and Mortgage.

The Principality Building Society catalog on APIs.io includes 1 Spectral governance ruleset.

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

🌐 Visit website 📡 Profile data on GitHub

36.2/100 thin ▬ flat Agent 20/100 agent aware Front door AI 1/6 silent saas Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

1 published contract

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

What this lets a business do 2

Business capabilities this provider's published APIs can perform, derived from its own contracts. Browse all capabilities →

Banking Customer Management

BC-1300

ATMBranch

GET /branches GET /atms

Banking Product Management

BC-1310

BCAPCA

GET /business-current-accounts GET /personal-current-accounts

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 36.2/100 · thin

Contract Quality 7.5 / 21

Developer Ergonomics 5.7 / 17

Access Clarity 9.7 / 17

Operational Transparency 0.6 / 11

Contract Governance 1.9 / 10

Discoverability 5.5 / 9

Regulatory Posture 3.0 / 15

Agent readiness — 20/100 · 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

Pagination 0 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

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/.

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Agent readiness — checks not met, largest first (exact, from this profile):

MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Rate-Limit Signaling +7 pts — OpenAPI responses document X-RateLimit-* / RateLimit headers (verified), else a rate_limits artifact or RateLimits link (documented)
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link
Registration Without a Human +6 pts — a `registration_endpoint` in the served RFC 8414 / OIDC discovery document

8 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 35.5 — up to +16.1 composite points
Developer Ergonomics scores 33.3 — up to +13.3 composite points
Operational Transparency scores 5.3 — up to +12.3 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

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 the provider profile at artifacts.apis.io/principality-building-society/apis.yml: open an issue on github.com/api-evangelist/principality-building-society to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Consumer Lending Licensing (UK, US, Canada credit licence registers)	regulated	19.2 (thin)	-	-
EU/EEA Payment and E-Money Institutions (PSD2 passports)	regulated	19.2 (thin)	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 2

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Open Banking Standard

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

OpenAPI

measured — observed by APIs.io (published)

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

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Principality Building Society API Rules

49 rules · 47 errors 1 warnings 1 info

SPECTRAL

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

Other 1

Properties that don't map to a standard resource type

CapabilityMap

CapabilityMap

Source (apis.yml)

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: saas
  license_evidence:
    not_product:
    - openbankinguk/opendata-api-spec-compiled
  open_source: unknown
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: low
  source:
  - openapi
  - pricing
  - repository-not-product
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
tags:
- Financial Services
- Banking
- Building Society
- Savings
- Mortgage
- 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
- Financial-Services
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
  - PI
  - PSD2
  - FAPI
  tags_raw:
  - 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:
  - Small Business
  tags_raw:
  - 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

Principality Building Society API — frequently asked questions

Does Principality Building Society have an API?

Yes. APIs.io lists 9 APIs from Principality Building Society, including OBIE Account & Transaction Information API (AIS - Standard, Out of Scope), OBIE Payment Initiation API (PIS - Standard, Out of Scope) and OBIE Confirmation of Funds API (CBPII - Standard, Out of Scope), and 6 more.

Is there an OpenAPI specification for the Principality Building Society API?

Yes. APIs.io indexes 6 OpenAPI specifications for Principality Building Society, each linked for download from this page.

How do I authenticate with the Principality Building Society API?

Principality Building Society uses bearer-token authentication (none · 0 schemes). The details are profiled on APIs.io as Principality Building Society Authentication.

Is the Principality Building Society API ready for AI agents?

Principality Building Society has a Kin Score of 36.2 out of 100 (thin) and an Agent Readiness score of 19.9 (agent-aware), scored by API Evangelist on 2026-11-06.

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