The RESO Web API is the Real Estate Standards Organization's OData-based standard for property listing data, together with the RESO Data Dictionary that defines the fields. It replaced the older RETS protocol and is the mechanism through which multiple listing services expose property data to brokers, portals and applications.
RESO Web API
RESO is a well-executed vertical standard, and it appears in insurance research for a reason worth recording.
- OData-based - The Web API standard builds on OData rather than inventing a bespoke query idiom, so conventional tooling works against it.
- A data dictionary - Field-level standardisation is arguably the more valuable half; the transport is the easy part.
- Certification - RESO certifies implementations, giving the market a legible conformance signal.
- Genuinely conformant implementations - Property-data providers publish standards-conformant OData contracts with documented paging bounds.
The insurance connection is a finding rather than a coincidence. The State of US Insurance APIs found that one of the largest property risk-data providers in American insurance — a company whose data underwrites homes — has exactly one real public contract, and it is a real-estate standard, not an insurance one. Its insurance-facing surface is not publicly contracted at all. When a company’s only standards-conformant API belongs to an adjacent industry, that tells you which market forced it to be legible.
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 Insurance APIs
The only real public contract published by one of American insurance's largest property risk-data providers is a real-estate standard, not an insurance one.
