RETS

RETS was how American property listing data moved for about twenty years. An XML-based request and response protocol with its own login, search and metadata semantics, it predates the conventions most developers now take for granted and requires a client written specifically for it. The Real Estate Standards Organization declared it end-of-life and directed the market to the OData-based RESO Web API as its successor.

• Bespoke, not RESTful - RETS defined its own transaction model rather than composing HTTP conventions, so tooling never generalised and every integration was purpose-built.
• Formally superseded - The RESO Web API and Data Dictionary replaced it, and NAR’s certification mandate applies to the successor, not to RETS.
• Still in production - The State of US Real Estate APIs found Trestle documenting RETS 1.8 alongside its certified OData surface, with a dedicated scope=rets OAuth scope issued next to the modern one. Retirement was announced; decommissioning was not completed.

The entry earns its place as a documented case of a standard that was properly replaced and did not go away. The successor is better designed, formally certified and industry-mandated, and the predecessor still answers requests because hundreds of independent cooperatives and their vendors each had to migrate on their own schedule and cost basis. Anyone modelling a standards migration should assume a long tail measured in years, and should budget for running both surfaces rather than for a cutover.

For an integrator the practical read is simpler: if a provider still advertises RETS, that is a signal about the age and layering of its stack, not merely a legacy footnote.

Industry: Real Estate