What is IDX in real estate terms?

IDX or Internet Data Exchange is why you and I are able to browse MLS listings online. More specifically, IDX is the set of rules, licenses, and technologies that allow real estate agents to access MLS listings, integrate them on their websites, and display them publicly.

Since the mid 1990’s, the Internet has taken a larger and larger role in the real estate industry. As recently as 2017, the National Association of Realtors (NAR) said that 51 percent of homebuyers found the home they purchased online. The percentage is even higher for young people.

This is largely thanks to IDX and availability of property listings online. We created this article to provide a comprehensive look at IDX. We’ll go point-by-point through its various aspects and provide everything you need to know about what it does, why it exists, and the advantages it offers.

What Is Broker Reciprocity?

Broker Reciprocity is the IDX rule that provides collective permission to display MLS listings. A broker that opts into IDX grants the right to other participants to display his listings and receives the right from other participants to display their listings.  In practice, Broker Reciprocity and IDX are used interchangeably.

In researching IDX, you’ll surely come across the term Broker Reciprocity. For all intents and purposes they are the same thing. Some MLS call it IDX; some call it Broker Reciprocity. They all provide the same service to agents and brokers.

Why Does IDX Exist?

IDX exists to help real estate agents market listings, attract leads, and close more sales.  By displaying listings online, agents can reach a larger audience and better match available homes to prospective buyers.

Before IDX, MLS listings were essentially closed to the public. When a homebuyer began looking for a home, she hired an agent. This agent searched the MLS database, looked for properties that matched the homebuyer’s needs, then showed them.

It’s not hard to see the problem. How would an agent know what properties matched the buyer’s needs better than the buyer herself?

The growth of the Internet provided opportunities to solve this problem. If agents could market listings online, they could reach more potential buyers, and encourage buyers to take a more active role in the buying process. The NAR developed IDX to make this possible.

How Does IDX Work?

IDX works by setting rules for brokers to pool listings, granting licenses for agents to access and use these listings, and providing technologies to display these listings on an agent’s website.

To begin allowing listings to be displayed online, the NAR wanted structure. The Internet, after all, is a decentralized, largely lawless venue. IDX ensures that MLS maintain control of their listings and that everyone plays by the rules.

What Are the Rules For IDX?

IDX rules provide the terms of use for IDX participants. They cover what an agent may do with IDX listings, how they must be displayed, how often downloads must be synchronized with the MLS database, and more.

For example, most IDX rules state that IDX listings may not be distributed to any person other than the agent, they must be displayed as is without any alterations by the agent, and downloads must be refreshed at least every 12 hours.

What Is an IDX License?

An IDX license is the agreement allowing an MLS member or vendor to access the MLS database and import listings for use in IDX. This document sets out the legal requirements of the various parties involved in setting up an IDX.

The terms of the IDX license vary by MLS, but many state what the MLS promises to provide, what the member or vendor may not do upon accessing the listings, and sets out the terms of responsibility if any rules are broken.

What Is an IDX Feed?

An IDX feed is the data connection between an agent’s website and the MLS that provides listings for display and updates these listings periodically as new property come on the market and others close or expire.  

To display MLS listings on your site, you need a link to the MLS. The IDX feed provides this link. In some cases your site will link directly with the MLS and import listings. In other cases your site will link to a third-party IDX vendor and display listings from their site.

The specific details of the IDX feed depend on the IDX technology used.

What Are the Different IDX Technologies?

There are four main IDX technologies: IDX Framing, FTP, RETS, and RESO Web API. Each of these technologies uses a unique method to access an MLS and import listings, and each has is strengths and weaknesses.

IDX Framing

Under IDX framing, your site will display listings that reside elsewhere on the web through a design feature known as a frame. Framing is one of the simplest and fastest ways to set up IDX on your site, but offers virtually nothing in the way of SEO.


Under FTP (or File Transfer Protocol), the listings displayed on your site reside on your website servers. This provides more SEO value than framing. But the way FTP transfer data is burdensome and inefficient. For each synchronization, the entire FTP file must be downloaded. This limits the number of syncs you can have each day and means your site may not have the most up-to-date information.


RETS or the Real Estate Transaction Standard provides a faster way to transfer and display listings. Rather than requiring a full file download, RETS updates listings incrementally. This allows for more listings updates while maintaining the strong SEO established under FTP.


The RESO Web API is the newest IDX technology. This technology uses an API or Application Programming Interface to call listings directly from an MLS and display them on an agent’s site. This continues the strong SEO methods established under FTP and RETS while reducing the need for local hosting.

What Is an IDX Vendor?

An IDX vendor is the company that accesses the MLS on behalf of an agent and does the technical work necessary to establish a data connection between the agent’s website and the MLS database.

What Is an IDX Plugin?

An IDX plugin is software sold by an IDX vendor that works at the receiving end of the data connection from the MLS. The IDX plugin accepts the raw MLS data and repackages it so it may be displayed on the agent website in a human-readable form.

The problem is that IDX feeds send data in coded form that cannot be understood by itself. So many IDX vendors sell plugins to interpret this data and tells it where to appear on the website so that the numbers that correspond with price appear in the price field.

As and example, consider Realtyna’s WPL plugin. This is a software package we’ve developed to help establish IDX on a WordPress site. Clients that install WPL are able to connect a RETS feed. WPL accepts this RETS feed and redirects each piece of data to the correct place on the client’s site.

What Are the Advantages of IDX for an Agent?

IDX offers several advantages for agents, including the ability to market properties to a larger audience online, engage home buyers more fully in the home buying process, and integrate property listings with other useful content for those who are active in the real estate market.

More and more leads are using the Internet to shop for homes. IDX can help agents access those leads. Those that choose not to use IDX, may limit the number of leads they capture or find it hard to compete at all.

How Do I Get IDX On My Website?

Getting IDX on your website depends on the technology used. Sometimes you can have your IDX up and running in less than a day. Sometimes it can take several days to establish a more robust data connection with the MLS.

We detail the typical process below.

Steps to get IDX on my website:

  1.     Call the MLS and request IDX paperwork
  2.     Ask MLS for a list of approved vendors
  3.     Contact several vendors for prices and technologies available
  4.     Choose the best vendor and technology that fits your budget
  5.     Complete the IDX paperwork
  6.     Vendor will establish data connection
  7.     Customize your site and IDX to fit your business model

How To Choose an IDX Vendor?

To choose an IDX vendor you need to keep in mind your preferred website platform, your preferred IDX technology, the lead capture features offered by vendor, the vendor’s payment structure, and ultimately the price.

To help, we’ve come up with a few key questions to ask your vendor when shopping for IDX.

  • Do you offer my preferred IDX technology (i.e. Framing, FTP, RETS, RESO Web API)?
  • What third-party themes are compatible with your service?
  • Where is the IDX data hosted (i.e. agent servers, vendor servers)?
  • Is your payment upfront or monthly?
  • What lead capture features are included in my purchase?
  • Do you offer co-mingling of several MLS?

Realtyna offers really good options for your IDX along with WPL PRO for your property listing WordPress Plugin.

Fancify is also the theme which works perfectly with Realtyna’s IDX solution.

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