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Real Estate Transaction Standards (RETS)

Quick Takeaways

  • RETS and RESO Web API both provide a common language for different computer systems to easily transfer real estate information.  
  • RETS is currently being phased out in favor of RESO Web API.
  • Adherence to these standards results in greater efficiency, cost savings, and enhanced user experience.

Short for Real Estate Transaction Standard, RETS 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 twenty years ago, RETS is being replaced by RESO Web API, a new standard built on current technology. RESO Web API uses open standards that are well supported in many fields.

Standards such as RETS and RESO Web API 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?

RETS Specifications (Legacy) (RESO, 2021)

“The Real Estate Transaction Standard (RETS) is a technology used to exchange standardized real estate data between all of the various types of software systems that handle real estate information. RETS is not a program, nor is it a language. It is a framework that can be adopted by any computer system to receive data from the Multiple Listing Service (MLS).

The RETS protocol has served the real estate industry for 20 years. Millions (if not billions) of real estate transactions have used this protocol and to that end it has served the industry well. As can be expected RETS is at the end of its life cycle and is being replaced by a newer standard (RESO Web API) utilizing current technologies.”

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 RETS?

RETS IDX - Frequently Asked Questions (MLS Technology, Inc.)

“RETS, like many computer standards, is a language that was built for a specific purpose, but the goal is the same: to have all computers that deal with real estate information "speak" the same language, so that you can use the same desktop computer program with any MLS that has adopted RETS.

For software developers and for providers of services like IDX sites, RETS means having to write programs to use only one language, the common language of RETS, in order to work with many different MLS systems. This means lower costs, more products, more competition among vendors, and faster implementations of new systems, all of which directly benefit people who work with real estate information as a living.”

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.”

RETS News

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.

T-RETS Extinction Countdown: The Comet Cometh for Dinosaur MLS Tech (RESO, Dec. 2, 2021)

With RESO Web API replacing RETS, RESO is publishing a tracker of multiple listing services who have already made the transition to the new standard. Includes reasons why it is important to transition sooner rather than later.

Is “Native” Data Dictionary on the Horizon for MLSs? NAR Proposal, Planning, and Questions (Organized RE, Oct. 14, 2021)

Discussion of the NAR MLS Technology and Emerging Issues Advisory Board’s recommendation of a best practice that multiple listing services to establish a native RESO Data Dictionary compliant MLS for all listing content available to MLS Participants and Subscribers.

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