What are the largest MLS real estate listings in the United States? This article provides the most updated list (as of 10/31/2021), along with links to their homepages and their 2021 Membership numbers. The National Association of REALTORS (NAR) is North America's largest trade association for real estate and has helped set the general requirements for IDX. However, the MLS space is a continually shifting landscape.
In December of 2020, a RESO official cited about 556 MLS's. Over the past year, the median subscriber count per MLS grew by about 18.8 percent. Feel free to bookmark this page for your resource of the top MLS's in the country. We'll continue to update it for you, so you have a single resource.
What is an MLS?
A multiple listing service (MLS), also known as a multiple listing system or multiple listings service, is a suite of services that real estate brokers use to establish contractual offers of compensation among brokers and accumulate and disseminate information to enable appraisals. It provides a database and software that real estate brokers use to widely share information about properties with other brokers who may represent potential buyers or wish to work with a seller's broker in finding a buyer for the property or asset. The listing data stored in an MLS's database is the proprietary information of the broker who has obtained a listing agreement with a property's seller.
In the late 1800s, real estate brokers regularly gathered at the offices of their local associations to share information about properties they were trying to sell. They agreed to compensate other brokers who helped sell those properties, and the first MLS was born, based on a fundamental principle that's unique to organized real estate: "Help me sell my inventory and I'll help you sell yours." [^1]
There is no single authoritative MLS and no universal data format. However, there is a data standard for MLS systems—the Real Estate Transaction Standard—which is being deployed across MLS solutions in North America. The Real Estate Standards Organization has been spearheading the industry's move to use more modern data formats, standard data definitions/fields, and coordinate leading industry organizations to build a new future of real estate data.
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[^1]: National Association of Realtors [^2]: Real Estate Standards Organization Case Study [^3]: Testimonials from satisfied customers.