As of June 2018, RESO (Real Estate Standards Organization) stopped supporting RETS (Real Estate Transaction Standard) in an official capacity. It ended certification services for RETS and shifted its resources to implementation and certification for the RESO Web API (application programming interface) to bring a new Internet data exchange (IDX) standard to the real estate industry.
The National Association of Realtors has mandated that all association members adopt RESO Web API, and, although RETS is still being used by majority of MLSs throughout the country, RESO hopes its more efficient, streamlined Web API will eventually phase out RETS.
RESO Web API provides a standardized interface to Multiple Listing Service (MLS) databases that allows IDX applications and websites to query listings in real time and return them in the search results. RETS and RESO Web API are different from each other because RETS is an XML feed and RESO Web API is an interface that allows for direct calls to an MLS server when a user performs a search.
RESO Web API provides a streamlined access point to an MLS database, but RETS requires duplication of the MLS database on an individual real estate website servers with incremental updates. RESO believes its Web API has certain advantages over RETS. Summarized, these advantages are:
- Streamlined data transfer protocols
- Common protocol for product development
- Lower hosting costs
- Enhanced security for MLS data
- Easier integration with third-party applications
- Reduction of coding requirements
Web API uses a more open approach to transferring real estate data with an architecture called Representational State Transfer (REST), which has a large world-wide community of developers. REST is intended to expand real estate technology development further into mobile and social media applications.
RESO Web API also uses a global technology protocol known as Open Data to bring consistency with free developers and other technologies in code writing. RESO’s goal is for Web API to serve as a catalyst for development of real estate technology in the same way that Google Maps served as a catalyst for mobile mapping technology development.
RESO has created a data dictionary for use with its Web API to further unify electronic property listings across more than 700 MLS in the United States. The dictionary provides definitions for the various resources and data fields that comprise a property listing.
The RESO Data Dictionary provides hundreds of definitions for every possible piece of information that could be necessary in an electronic property listing. It’s called the “Rosetta Stone” for real estate data. It’s designed to provide predictability in how property listing data are structured and stored across all MLSs.
RESO offers RESO Web API Certification for Multiple Listing Services, Associations of Realtors, Technology Partners and Brokerages. Application for RESO Web API certification is open to any type of organization.
Organizations who are certified to use RESO’s Data Dictionary can be certified for Web API free of cost; others have to pay a fee that ranges from $400 to $12,875, depending on the organization’s gross revenue. RESO Web API requires testing of MLS servers during the certification process for OpenID security, and RESO confirms test results before certification.