OPDA member firms

Who OPDA actually is — the 13 firms that launched it in 2023, the wider association membership that has grown around it, and the seven firms who have achieved OPDA Technical Certification by evidencing PDTF implementation.

Note on terminology: per openpropdata.org.uk/our-members/, "Membership with OPDA has one simple tier" — all members get the same access, voting, and decision-making rights. The founding / association / Technical Certification split used on this page is an analytical framing for the knowledge base; it is not a constitutional distinction.

The 13 founding members (launched OPDA in 2023)

Identified from the "Our Members → Founding Members" section of openpropdata.org.uk, cross-referenced against the May–Dec 2023 press posts on the OPDA blog announcing the formation. Each is mapped to its primary bounded context (one firm can touch multiple — primary is the dominant one).

✓ = holds OPDA Technical Certification.

Founder distribution across contexts

How the 13 founders spread across the six primary bounded contexts:

• Property Data Services — 5 firms (Sprift, Inventory Base, TM Group, Kotini, Groundsure)
• Property Technology — 3 firms (Moverly, Coadjute, PEXA)
• Estate Agency — 2 firms (OnTheMarket, Homely)
• Mortgage Lending — 2 firms (OMS, United Trust Bank)
• Conveyancing (Legal) — 1 firm (LMS)
• Surveying / Valuation — 0 founding members (the most under-represented context — RICS is on DPMSG but no surveyor was an OPDA founder)

The shape of the founding coalition explains a lot about what's well-covered in PDTF today (data services, listing data, lending integration) and where the gaps will need new members: surveying in particular, and letting-specific use cases.

The shape of the founding coalition

Technical Certification (as of May 2026)

Seven of the 13 founding members have evidenced PDTF implementation through OPDA's rigorous Technical Certification process. Per OPDA's own page, this certifies that the firm's systems, data policies, and working practices align with OPDA principles and enable interoperability across the property community.

• Kotini
• Groundsure
• Inventory Base
• PEXA
• LMS
• Sprift
• United Trust Bank

Association members (joined after launch)

Membership has grown materially since the 2023 launch. Association members identified from the same "Our Members" section, with press posts in our archive corroborating join dates where known.

Lenders / banks

• HSBC UK — joined Aug 2024 ("HSBC UK joins forces with OPDA")
• Nationwide Building Society — joined OPDA's campaign
• NatWest Group — joined the OPDA campaign
• Atom Bank — digital lender (atombank.co.uk)
• Halifax — Lloyds Banking Group retail brand, listed separately on our-members
• BM Solutions — Lloyds Banking Group buy-to-let brand, listed separately on our-members
• Scottish Widows — Lloyds Banking Group brand, listed separately on our-members

Note: "Lloyds Banking Group" (the umbrella entity) is not itself a logo on openpropdata.org.uk/our-members/ — only the three sub-brands (Halifax, BM Solutions, Scottish Widows) appear. Santander is not listed as an OPDA member on that page either; it appears in our archive only as the author of the "Fixing the Broken Chain" report (see opda-reports).

Intermediaries and tech

• Mortgage Advice Bureau (MAB) — joined as the first intermediary network member
• Smoove
• Finova
• Phoebus
• Home Sale Pack (HSP) — upfront-information / sale-pack platform (homesalepack.com)
• View My Chain (VMC) — transaction-chain visibility platform (viewmychain.com)
• Lenderhive
• Movera (formerly Mulberry)
• Movemnt — joined to streamline homebuying
• Experian
• Houseful — property data and analytics group, parent of Zoopla and Hometrack (houseful.co.uk)
• Hometrack
• Open Property — proptech platform (openproperty.io)
• Simply Conveyancing — conveyancing firm (simplyconveyancing.co.uk)
• Survey Shack — surveying member (survey-shack.com); fills the surveying gap noted in the founders' context distribution
• Connells Group — "Digital Sale Ready" pilot on propdata.org.uk
• L&C Mortgages
• Novus Strategy
• Armalytix
• Credas
• Clozy
• C2C
• Property Deals Insight
• e4 (UK)

Full logo wall at openpropdata.org.uk/our-members/.

Membership tiers and fees

OPDA operates a single membership tier — per openpropdata.org.uk/our-members/, "Membership with OPDA has one simple tier. All members benefit from the same access, decision making, influencing, and collaborative working." Annual fees are banded by firm size and turnover, per OPDA's Membership benefits and fee structure document:

• Start-ups and micro businesses (1–5 FTE and <£100k turnover) — £3,000 p.a.
• SME businesses (5–50 FTE and <£1m turnover) — £6,000 p.a.
• Organisations and larger businesses (50+ FTE and/or >£1m turnover) — £10,000 p.a.

Source: source/01-organisation/constitution-and-policies/Membership benefits and fee structure.pdf. Fees are paid annually in advance; FTE and turnover are self-declared on application and cross-checked against Companies House.

WP custom post type — what's officially indexed

For reference: querying the OPDA WordPress REST API at /wp-json/wp/v2/member returns only 4 member custom posts with dedicated landing pages — Moverly, OnTheMarket, PEXA, and Sprift. The other 9 founders + all association members appear as logos on the /our-members/ page but don't have dedicated /member/<slug>/ URLs. This is a publishing decision (probably to feature key partners), not a statement about membership status.

Implications for the linked-data project

Three things worth carrying forward from the membership map:

• Stakeholder engagement for the semantic-modelling work has natural starting points: the seven Technical Certification holders have already evidenced PDTF implementation, so they're the natural early reviewers for the ontology / data dictionary / SHACL shapes.
• Conformance scheme design (per ToIP Layer 4 governance) should build on what Technical Certification already does — re-framing it in the language of a ToIP-style Ecosystem Governance Framework + Trust Registry.
• Banking representation grew materially post-launch: HSBC UK, Nationwide, NatWest, Atom Bank, and the three Lloyds Banking Group sub-brands (Halifax, BM Solutions, Scottish Widows) joined the founding United Trust Bank. This is the proof-point that the Open Banking analogy is operationally working: many of the same lenders that participated in Open Banking are joining its property-data analogue.