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Real Estate Transaction Standards (RETS)

RESO Web API

Quick Takeaways

  • RESO Web API provides a common language for different computer systems to easily transfer real estate information.  
  • RETS has been phased out in favor of RESO Web API.
  • Adherence to open standards results in greater efficiency, cost savings, and enhanced user experience.

RESO Web API provides a common language so that computers can more easily transfer real estate information, such as MLS data, to other computer programs or websites.  After its creation as RETS twenty years ago, it was replaced with RESO Web API, a new standard built on current technology. RESO Web API uses open standards that are well supported in many fields.

Open standards allow different systems to communicate easily. Adherence to these standards results in greater efficiency, cost savings, and enhanced user experience. They also encourage greater competition among vendors by allowing anyone free access to the specifications.

As technology changes, so do best practices, data standards, and transport protocol. The Real Estate Standards Organization (RESO) creates, certifies, and updates standards as they are needed. Many multiple listing services are converting their systems from RETS to RESO Web API with many more to make the transition in the near future.

See References for more information.

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References

NAR Library & Archives has already done the research for you. References (formerly Field Guides) offer links to articles, eBooks, websites, statistics, and more to provide a comprehensive overview of perspectives. EBSCO articles (E) are available only to NAR members and require the member's nar.realtor login.

What Is RETS?

About the Real Estate Standards Organization (RESO) (RESO, 2023)

“In 2002, NAR created an official workgroup, which would eventually become RESO. This workgroup created the first version of the well-documented Real Estate Transaction Standard (RETS).

RESO was incorporated in November 2011 as an independent, not-for-profit trade organization. Soon after, it released the industry’s Data Dictionary, followed by the RESO Web API, which replaced RETS. Over 500 MLSs have been certified on these standards.”

RESO Web API (RESO, 2021)

“The RESO Web API is the modern way to transport data in the real estate industry. It is built on well-known, open technology standards so that any organization can use it to deliver or receive data quickly and efficiently.”

Real Estate Transaction Standards (RETS) Web API (National Association of REALTORS®)

“MLS organizations owned and operated by associations of REALTORS® are required to adopt and implement the Real Estate Standards Organization (RESO) Standards, including:

  • the RESO Data Dictionary by January 1, 2016;
  • the RESO Web API by June 30, 2016; and
  • will keep current by implementing new releases of RESO Standards within one (1) year from ratification.”

Why RESO Web API?

What Is RESO Web API Technology? (Real Estate Bees, Nov. 6, 2023)

“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.”

Why Open Standards are Vital to the Real Estate Industry (RESO, 2019)

“A single set of ubiquitous open standards for real estate creates:

  • The largest and most attractive marketplace for innovators.
  • Great technical efficiencies; allowing innovators to focus on the software we see - instead of expending effort on moving data.”

RESO Web API News

Web API Transition Guide: Transitioning Your Customers to Reso Web API (RESO, Feb. 21, 2023)

“Transitioning your customer base from RETS to a certified RESO Web API service requires significant planning and communication. To provide you a path forward, RESO collaborated with MLS organizations that have already converted their customers to Web API to bring you this best practices guide.”

RESO 2022 End-of-Year Update (RESO, Dec. 1, 2022)

This overview of the past year includes updates on the transition from RETS to RESO Web API, new standards and features, courses, and translations.

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