The RESO Universal Property Identifier is a URN-based scheme for identifying a piece of real property unambiguously across systems, jurisdictions and data providers. Version 2.0 encodes country, jurisdiction and the local parcel or assessor identifier into a single resolvable string, giving American real estate the shared property key it otherwise lacks. Both “Universal Property Identifier” and “Universal Parcel Identifier” appear in circulation for the same acronym.
RESO UPI
The RESO Universal Property Identifier answers a question that sounds trivial and is not: how do two systems agree they are talking about the same piece of land? American property records are maintained county by county, with local parcel and assessor numbering that collides freely across jurisdictions. UPI 2.0 wraps that local identifier in a URN alongside country and jurisdiction, producing a key that survives leaving the county that issued it.
- URN-based - A structured, resolvable string rather than an opaque surrogate key, so the identifier carries its own provenance.
- Built on the local record - It composes the existing parcel or assessor identifier rather than replacing it, which is why adoption is possible at all.
- Certified separately - RESO certifies UPI implementations independently of the Web API and Data Dictionary. Trestle is the first multiple-listing data distributor to hold UPI v2.0 certification.
- Two names in circulation - Sources use “Universal Property Identifier” and “Universal Parcel Identifier” for the same acronym. Catalogs and integrations should accept both.
Worth reading alongside the UPRN, Britain’s equivalent. The two schemes solve the same problem and have had markedly different fates, for a reason that has nothing to do with their technical design. UPRN is issued by Ordnance Survey and GeoPlace against a public addressing register, so anyone can resolve one. UPI is certified against listing data that sits behind an MLS licence, so the identifier is standardised but the record it points at is not reachable without a contract.
The State of US Real Estate APIs found the certified distributor holding the first UPI v2.0 certification
also serves an OData $metadata document that returns 401 to any caller without an executed licence.
A universal identifier is only as universal as the thing it resolves against.
Referenced in API Evangelist papers
This standard shows up in my published research. These reports read the machine-readable evidence provider by provider — and put this standard in the context of a real sector.
The State of US Real Estate APIs
Trestle is the first multiple-listing data distributor certified on UPI v2.0 — and its OData metadata document still returns 401 without an executed MLS licence.
