Yes, we can integrate third-party listing systems to ensure your website always reflects your latest properties.
Three terms get used interchangeably and they operate at different layers. Getting them straight makes every downstream decision easier.
MLS is the database your local board maintains. IDX is the licensing and display framework that governs who may show that data publicly and under what conditions. RESO Web API is the technical protocol that delivers it.
IDX is not an alternative to RESO. It is the rulebook layered on top of whichever protocol moves the data.
RETS was the standard for nearly two decades. RESO deprecated it in 2018 and retirement accelerated through 2024, with at least one major vendor shutting off RETS integrations entirely at the end of that year. RESO Web API 2.0 is a RESTful, OData-based interface with OAuth 2.0 authentication, and it is the only protocol worth targeting for a new build.
A minority of boards still expose RETS endpoints for backward compatibility. If your market is one of them, the right architecture is RESO-first with a RETS fallback, not a RETS build that will need replacing.
NAR sets minimum IDX standards through Policy Statement 7.58. Each local MLS then writes its own rules that meet or exceed those minimums. Local rules can be more restrictive, never looser.
That means attribution requirements, refresh frequency, which fields may be displayed, and whether listings can be indexed differ between boards. A firm operating across multiple MLS territories is complying with several rulebooks at once. This is a real scoping factor, not a formality.
The August 2024 NAR settlement also changed how cooperation and compensation fields appear in feeds, so any new build needs to account for the updated schema rather than assuming older field mappings still apply.
This is the decision that most affects whether your listings do anything for your search visibility.
iframe and widget solutions embed a third party's search interface into your page. They are inexpensive and fast to deploy. The listings live on someone else's domain, so they contribute little or nothing to your own organic visibility.
API-based integration pulls listing data through RESO and renders it as native pages on your domain. Each property becomes an indexable URL you own, with your design, your speed, and your schema markup. This is more work to build and it is the only version that turns listings into a search asset rather than a borrowed widget.
If the goal is capturing search activity on your own domain instead of ceding it to the portals, API-based is the only real answer.
We start with which MLS boards you need, what their individual display rules require, how many listings you will carry, and how quickly status changes need to propagate. We also ask an unglamorous question: does your team actually maintain accurate data in the MLS, or does the authoritative version live somewhere else? Building a sync on top of a bad input just distributes the problem faster.
Then we plan for failure. Feeds break, credentials expire, boards change schemas. Sites we build fall back to last known good data and alert someone, rather than showing an empty search page to a buyer.
Many IDX setups default to forcing registration before a visitor can view results. It reliably suppresses engagement. Letting people search freely with well-placed optional capture almost always produces more qualified leads than a hard gate, even though it produces fewer raw form fills.
For related detail see what makes a great residential real estate website and how we connect sites to a CRM, or learn more about our residential real estate practice.
