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Understanding Real Estate Listing Data: The Difference Between IDX and RETS

Understanding Real Estate Listing Data: The Difference Between IDX and RETS

12 min read
Understanding Real Estate Listing Data: The Difference Between IDX and RETS

Incorporating MLS listing data on a real estate agent’s website can be fairly complicated, so it’s no wonder we get a lot of questions about the difference between IDX and RETS. But before we get into that, a brief vocabulary lesson is in order. (Don’t worry: We’ll leave out as much of the tech speak as we can.)

First, let’s define some of the relevant terms.

IDX (Internet Data Exchange) – This refers to the data exchange between an MLS board’s database and a realtor’s website. Sometimes, IDX is used to refer to a specific method of data exchange, most of which are outlined below. IDX has to do with public MLS search, and is viewed as a form of advertising. The listings that are displayed here are only those allowed by other participants, but almost always includes the vast majority of the MLS database.

RETS (Real Estate Transaction Standard)

RETS is used to give brokers, agents and third parties access to listing and transaction data. MLSs nationwide are moving to adopt RETS as the industry standard because it drastically simplifies the process of getting listing data from an MLS to an agent’s site. Key benefits include customization of how the listing data is displayed, fresh listing data (updated as often as every hour), and content added to the site (SEO – search engine optimization). The one main drawback is that the data feed is impossible to use by itself. In other words, you need a trained professional or additional software to make sense of it.

FTP (File Transfer Protocol)

Implemented before RETS, this is a standard protocol used to transfer files from one host (the MLS) to another (the agent). The listing database on the agent’s website is synchronized with the MLS database, and updates usually once or twice a day. FTP also has the benefits of SEO and customization, though the data is not as recent as it could be with RETS. It’s very important to note that there is no set standard with FTP between MLSs. Since each MLS has their own unique way of doing things, using FTP can cost a whole lot more.


An iframe is a MLS search window/HTML element that agents can put on their site. Most often, these are provided by an MLS for free, and are very easy to use. Implementation requires little more than copying/pasting a link into the site. Though agents commonly refer to iframes as IDX, they’re not the same, as no data is actually transferred. Content is not added to the agent’s site, and customization is limited. This means that in addition to being unattractive, the agent’s website doesn’t receive any content. There is no SEO benefit.

After reading the definitions above, you’ll understand that RETS is actually an option for IDX, along with its precursor, FTP. But now that you know, why should you care? Well, the answer to that depends largely on what you’re looking for.

Let’s assume that all you want is an MLS search feature for your website, and also assume that design and content are not important. You might think that because of the ease of use and low cost (free), the iframe would be a good choice.

But it’s not quite that simple.

Sure, you’ll have the search feature built into your site–but does it really get the job done? Remember that content is king, and sites with more content rank higher than those without it. Since iframes don’t actually add any content to your site, the Googles and the Bings of the world don’t have much to judge your site by.

Now, compare this with a site that actually has listing data (content) on it. Imagine hundreds, if not thousands of pages of quality listing data in the market you serve vs. one “Listing Search” iframe. The fact is that sites with content will rank higher than your own, leaving you at the bottom (and unseen) part of the list.

If content is something you want, it appears that there are two options to choose from–FTP and RETS. Both will improve your ranking on search engines, but RETS will provide you with data that is both more accurate and easier to work with.

Why? Well, the FTP standard forces you to download the entire database of listings in bulk each time you want to update your records. This can be incredibly time-consuming, especially when it comes to MLSs with many listings. Because of this, with FTP, listings are sometimes only updated once per week.

With RETS, on the other hand, listings are downloaded in more manageable segments, and only those that have been recently added or changed will need to be updated. This means that the listings can be refreshed more regularly, giving site visitors more current listing data.

As MLSs across the country continue to adopt the RETS standard, the industry will enjoy both its technical and practical benefits. Techies will have a much easier time setting up their solutions, and real estate professionals will be able to provide significantly more value to their clients.

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