How Is IDX Different From RESO Web API?

Introduction to Real Estate Data Sharing

Real estate data sharing is essential in today’s property market. It fuels websites with listings that attract buyers and helps sellers by increasing the visibility of their properties. 

Data like prices, photos, and features must be accessible and current to be valuable. IDX, or Internet Data Exchange, enables realtors to show MLS listings on their websites, providing a broad selection for potential buyers. 

Meanwhile, RESO Web API, developed by the Real Estate Standards Organization, is a more modern data-sharing format. It uses web technologies to ensure real estate data is standardized, making it easier for various software to interact seamlessly. 

Both systems aim to streamline real estate transactions by improving how data is shared across different platforms, ensuring users have the most accurate information at their fingertips. 

This article explains the differences between IDX vs Reso Web API concepts. Understanding the difference between the two is essential for real estate professionals who want to use these technologies to enhance their business operations.

If you are not familiar with MLs, you may want to read our What is Multiple Listing Service ( MLS ) in Real Estate guide.

What is IDX (Internet Data Exchange)?

IDX (Internet Data Exchange) and RESO Web API (Real Estate Standards Organization Web API) are technologies that share real estate listing data among different systems.

IDX is a framework that allows real estate professionals to display MLS (Multiple Listing Service) listings on their websites. It will enable agents to create custom search functionality, show property details, and other features that allow users to search and view listings directly on their websites.

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IDX is also beneficial for clients as it allows them to search for properties on the agent’s website and see up-to-date listings.

In a few words: IDX, short for Internet Data Exchange, is like a set of guidelines and tools that control how property information goes from the official real estate list to your website and then to the people you’re selling to. 

It manages how your site gets this info from the real estate list and shows it to everyone.

You can read more about this subject here: What Is IDX (Internet Data Exchange) – The Complete Guide.

Your real estate website can show property listings in a few different ways, which are all part of what’s called IDX:

With iFrames, your website can display listings sent from your MLS provider. They’re like little windows or boxes on your site that show these listings. While iFrames are easy to set up, they don’t help your site show up better in Google searches because Google can’t see what’s inside them.

FTP is a more technical way to send listing data between businesses. It’s not very user-friendly and slow in getting updates, so it’s not a favorite for those who work with MLS listings.

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How MLS benefits from RESO Data Standards

RETS has been the primary way real estate pros in the US get their listing information. It’s like a common language that lets different real estate computer systems talk to each other and share information. But there’s a newer system developed that’s aiming to be even better at this.

That new system is the RESO Web API. It’s the freshest way to move and use listing data, designed by the same folks looking to improve RETS. Next up, we’ll get into more detail about it.

What is RESO Web API?

On the other hand, RESO Web API is a technology standard that allows different systems to share and exchange real estate data consistently and standardized. 

The first appearance of the RESO Web API was in 2017. 

👌 RESO HIstory
The Real Estate Standards Organization (RESO) released a free Web API tool for real estate software developers on March 16, 2017!

API stands for “Application Programming Interface,” as the name suggests, the RESO API is a tool that allows MLS providers to send out their listing data to their members more efficiently.

The RESO API is a step up from the old system, RETS, bringing along some exciting improvements that make things easier and better for everyone in real estate.

So, what’s good about this new RESO API? 

Cheaper: It’s cheaper to keep up and run on your website, bends more easily to fit your needs, works better with other apps and services you might be using, and makes getting and sharing MLS data smoother and faster.

  1. Multiple MLS: You can integrate various MLS systems on your platforms using Reso API.
  2. Data Sharing: with this API, you can share data between different systems, such as a brokerage’s CRM and MLS or a real estate website and MLS.
  3. Format Standardization: RESO Web API enables different systems to share and exchange data in a standardized format, eliminating the need for custom integrations between systems.
  4. Multiple applications: the same Reso Web API can be used to develop a website, a desktop platform, or a mobile application.

So, if IDX is a method that allows real estate agents and brokers to display listings from other brokers on their websites, the RESO WEB API is the tool that enables developers to do just that.

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IDX Websites created with MLS Import Plugin

Technical Specifications: IDX vs. RESO Web API

IDX and RESO Web API serve the same industry but in different ways, with unique specifications.

IDX systems often rely on older technology, which typically involves pulling data from the Multiple Listing Service (MLS) in a less dynamic fashion. 

This data is often displayed through iFrames or other methods that don’t allow much customization or integration into the website’s search engine optimization efforts. 

The IDX data sync can sometimes be slow, with updates happening only a few times a day, which means listings may only sometimes be current.

On the other hand, RESO Web API is a newer technology adhering to the latest web standards. It uses a standardized API (Application Programming Interface) approach, which allows real-time data access and interaction.

 It means that when information is updated in the MLS, it’s reflected almost immediately on the website using the API. This immediacy is possible because the RESO Web API facilitates a more direct and seamless connection to the MLS databases.

The RESO Web API is designed for today’s web development, working smoothly with different coding languages and tools. It allows developers to build more tailored features on real estate sites. 

It also uses the RESO Data Dictionary to guarantee property data is uniform and can work together across various MLS systems, which is essential for developers and real estate pros working with multiple MLS databases.

Advantages and Disadvantages of Each System

IDX Advantages:

  • It lets real estate websites show lots of listings, which can attract more visitors.
  • It’s widely used, so many people in the industry are familiar with how it works.

IDX Disadvantages:

  • The listings aren’t always up-to-the-minute because updates can be slow.
  • It doesn’t help your website rank better on search engines like Google.

RESO Web API Advantages:

  • It updates listings super fast, so your website always has the latest info.
  • It works well with modern web tech, giving you more control to create a unique website.
  • It makes sure property details are the same across different real estate systems.

RESO Web API Disadvantages:

  • It might require more tech-savvy to set up and use than IDX.
  • Since it’s newer, some might need to be more familiar with it than IDX.

IDX in Action

Imagine a real estate agent named Sarah who has a website where she wants to showcase homes for sale. She uses an IDX system that takes information from her local MLS and displays it on her site. 

Visitors to Sarah’s website can see various listings, not just Sarah’s, but also homes listed by other agents in the area. However, if a house is sold and the listing is updated on the MLS, there might be a delay before this change appears on Sarah’s site. 

Also, Sarah’s website might not climb up in Google search rankings because of how IDX presents the listings.

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RESO Web API in Action

On the other side, let’s consider a broker named Alex, who’s tech-savvy and wants his website to be both current and customizable. 

He chooses to use the RESO Web API. Alex’s website to have real-time access to the MLS database. So, if a new home comes on the market or a price changes, Alex’s website updates almost instantly. 

Additionally, because the RESO Web API is flexible, Alex can create special search tools and features that make his website stand out and rank higher on search engines. 

The data from the MLS also integrates with other applications Alex uses, thanks to the standardized format set by the RESO Data Dictionary.

MLSImport plugin is one of the MLS / IDX WordPress plugins built around RESO WEB API – so any website made around it will benefit from the fast data update, flexibility of design, and the possibility of increasing Search Engine exposure.

Is real estate IDX obsolete?

It is inaccurate to say that real estate IDX (Internet Data Exchange) is obsolete. IDX is a method that allows real estate agents and brokers to display listings from other brokers on their websites.

However, IDX has some limitations and is being replaced by more advanced technologies like RESO Web API, which allows for more flexibility in data access and usage and the ability to integrate data from multiple MLSs.

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So, IDX is still used by many real estate professionals. Still, it is less efficient and advanced than RESO Web API, which is becoming the industry standard for data exchange and integration between MLS systems.


In conclusion, IDX and RESO Web API are important tools that help real estate professionals share property listings on their websites. 

IDX is more accessible for those who prefer a straightforward approach, but it doesn’t update listings in real time or help improve website search rankings. 

On the flip side, RESO Web API provides fresher listing updates and fits better with modern website features, which can help professionals stand out online. 

Real estate agents and brokers should weigh these differences carefully to decide which system aligns best with their business goals and technical capabilities, ensuring they provide the best possible service to their clients.


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