For agents

IDX

Also called Internet Data Exchange, IDX search

Definition

Internet Data Exchange: the MLS program that lets member brokers and their agents show other brokerages’ active listings on their own websites and apps, under display rules set by each MLS.

With IDX, a buyer can search the whole market on your website instead of a portal’s. Your MLS licenses the data, and its rules decide what you can show and how.

How does IDX work?

Brokers who belong to an MLS agree to let one another display their listings online. The MLS sends that data to the broker, or to a website vendor the broker authorizes, through an IDX feed. The website stores the listings, refreshes them on a schedule and shows them in a search.

Agents get IDX through their broker’s MLS membership, and the MLS approves the website or vendor before any data flows. Under NAR’s IDX policy, the data has to be refreshed at least every 12 hours. Many sites refresh far more often, so new listings and price changes show up much sooner.

What do IDX display rules require?

Each MLS writes its own IDX rules within NAR’s policy, so the details vary by market. The common ones: every listing carries listing attribution naming the listing brokerage, your own brokerage is clearly identified, and the MLS’s disclaimer appears with the data.

Some information never appears on an IDX site: seller names and contact details, showing instructions, security details and fields the MLS keeps confidential. A seller can also tell the listing agent to keep a listing, or just its address, off the internet, and IDX sites must honor that.

Which statuses you can show, such as pending or sold, also depends on your MLS.

IDX, VOW, RETS and the RESO Web API: what’s the difference?

IDX and a VOW are two ways to show MLS data to the public. IDX is open to any visitor. A VOW, or virtual office website, asks visitors to register and accept terms first, and in return can show more of the MLS’s data.

RETS and the RESO Web API aren’t display programs. They’re the pipes that carry the data. RETS is the older format, and RESO has deprecated it and no longer supports it. The RESO Web API is the modern replacement, and it uses the RESO Data Dictionary so fields are named the same way from one MLS to the next.

What should an IDX website do for you?

The listings are the same everywhere. What differs is the search around them: a map buyers can use on a phone, filters that match how people shop, and listing pages with an easy way to ask you a question.

Look for three more things. Your neighborhood pages should show current MLS listings, not just text. Saving homes shouldn’t require an account first. And every inquiry should reach you right away, because speed to lead is the whole point of having buyers search on your site instead of a portal.

Common mistakes

  • Assuming IDX rules are the same in every market. Each MLS writes its own within NAR’s policy.
  • Removing or shrinking the listing brokerage’s courtesy line to tidy up a design.
  • Showing sold or pending data your MLS doesn’t allow on IDX displays.
  • Picking a vendor without asking how often it refreshes listings and whether it uses the RESO Web API.

Questions

Do I need my broker’s permission to have an IDX website?

Yes. IDX access runs through your broker’s MLS membership, so your broker and your MLS both have a say. Many website vendors handle the MLS paperwork with you.

Is IDX the same as the MLS?

No. The MLS is the database its member brokers share. IDX is the program that lets those brokers show part of that database to the public on their own websites.

How often do IDX listings update?

NAR’s IDX policy requires a refresh at least every 12 hours. Many vendors update far more often, so ask yours for its actual schedule.

Can I show sold homes on my IDX website?

Only where your MLS allows it. Rules on sold data differ from one MLS to the next, and some markets build up sold history only as homes close.

Sources

  1. NAR, Internet Data Exchange (IDX) Policy, Policy Statement 7.58
  2. RESO, RESO Web API
  3. RESO, Data Dictionary

Written and checked by the Broker & Agent team on October 2, 2026. General information, not legal, tax or lending advice. Something out of date? Tell us.

Related terms

The whole glossary
IDX feedThe data connection an MLS licenses to a broker or an approved website vendor, delivering active listings, photos and updates so an IDX website can show the market and keep it current.In the glossary Multiple listing serviceA private database where member brokerages share listings so agents can find homes for their buyers. Each MLS covers a local or regional market and sets its own rules and statuses, and most home search websites show its listings.Full guide VOWVirtual Office Website: a brokerage website where consumers register, accept terms of use and form a relationship with the broker before searching MLS data, which can include more detail than a public IDX search shows.In the glossary RESO Web APIThe Real Estate Standards Organization’s modern standard for moving MLS data between systems over the web. It replaces the older RETS standard and uses the RESO Data Dictionary’s shared field names.In the glossary Listing attributionThe credit line naming the brokerage, and often the agent, that holds a listing. MLS rules require it on listings shown through IDX, usually in a set place and a readable type size.In the glossary Broker reciprocityAn older name, still used by some MLSs, for IDX: brokers in an MLS agree to let one another show their listings on their own websites, each listing credited to the brokerage that holds it.In the glossary

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