Real Estate Listing Data Terminology: What are MLS, IDX, RETS, RESO, VOW, and DDF?

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Do you find yourself confused when searching for IDX solutions and seeing acronyms like MLS, IDX, RETS, RESO, VOW, and DDF? You’re not alone! While these terms might seem intimidating and difficult to understand, they are straightforward. Knowing what each of these means can be an invaluable tool when developing real estate applications and websites.

Real Estate Listing Data Terminology: What are MLS, IDX, RETS, RESO, VOW, and DDF?

IDX for Real Estate Websites

The first acronym to understand is IDX, otherwise known as Internet Data Exchange. Internet Data Exchange is a method of transmitting a Multiple Listing Service’s listings and other real estate information to agent and broker websites. Adding IDX to real estate websites allows professionals to display things like active listings and property details.

A good IDX solution will help agents and brokers easily create custom websites with listing search capabilities. IDX is specifically designed for the real estate industry, where the ability to quickly share listings among agents and potential homebuyers is critical, providing valuable access to accurate and detailed real estate data.


MLS, or Multiple Listing Service, is a database of real estate information, grouped by state or region, that many agents and brokers join to share data on a variety of properties they’re currently selling. MLS’s enable agents and brokers to help one another find buyers for their property in a quicker time frame.


RETS - Real Estate Transaction Standard - is a technology used to exchange standardized real estate data between various types of software systems that handle real estate information. It’s commonly used among IDX real estate websites and other applications.

RETS was created as a way for multiple listing services to share massive amounts of detailed property data with brokers, agents, and vendors in a secure, consistent format. Although RETS is still the most widely used technology for distributing real estate data, RESO Web API is a more modern format that is being widely adopted by data providers and replacing RETS.


RESO, the Real Estate Standards Organization, is an amazing resource for those working in the real estate industry. It is a professional standards development organization dedicated to increasing data liquidity across platforms and marketplaces. RESO is responsible for developing and maintaining the RETS and Web API standards.

In short, RESO defines the basic standards on which real estate applications are built. IDX for real estate websites is based on these standards, meaning users can search for properties online consistently without regard for the underlying implementation or database, which helps agents control how their listings appear on websites.


VOW means Virtual Office Website. This is a type of back-office application that differs from standard IDX for real estate websites. Generally, it provides more detailed information and includes off-market MLS data. This comprehensive service allows real estate agents to access detailed property information, share listings, and interact with customers through their established website. This type of IDX enables agents to efficiently manage client requests and track activity on the website.


DDF is a system that allows real estate brokers to share their listings with other brokers across Canada. DDF makes it easier for brokers to market their properties to potential buyers and helps increase the visibility of their listings. This means Canadian users can add listings from across the country on their IDX real estate website. Some states in the U.S. have a similar system.


Being familiar with various types of technologies helps you make informed decisions when building an IDX real estate website. The expertise of SimplyRETS in these technologies allows you to create an effective and intuitive website for your own real estate business. With our help, you can transform the way clients interact with your listing information. To start building your online presence now, head to our website to explore more!


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