If you've ever asked a web developer for "MLS on my website," you've probably heard a flood of acronyms back: IDX, VOW, RETS, RESO, framed, organic. This guide explains what they mean in plain English — and what actually matters when you're choosing a setup.
MLS: where the data lives
Your Multiple Listing Service (MLS) is the database where brokers share listing information. It's owned and run by a local or regional organization, and access is governed by its rules. The MLS is the source of the data — your website never "is" the MLS, it only displays information the MLS allows.
IDX: displaying listings on your website
IDX (Internet Data Exchange) is the policy and framework that lets participating brokers display each other's active listings on their websites. When you add property search to your site, you're using IDX.
In practice, you don't connect to the MLS directly. You subscribe to an IDX provider — a company approved by your MLS that pulls the feed and gives you search tools, listing pages and lead capture.
Before an IDX provider can activate your feed, your MLS normally requires paperwork signed by you and your broker. Plan for that approval time when you set a launch date.
VOW: a more detailed, registration-based option
A VOW (Virtual Office Website) also displays MLS data, but it's designed for a brokerage-client relationship. Visitors typically must register and agree to terms before seeing listings, and in return a VOW may show data that a public IDX display can't — depending on your MLS rules.
For most agents, a standard IDX setup is what they need. VOWs are more common with brokerages that have specific data or compliance requirements.
RETS and RESO Web API: how the data moves
These are the technical pipes behind the scenes:
- RETS was the long-standing standard for transferring listing data.
- RESO Web API is the modern standard the industry has moved toward.
You rarely need to handle either yourself — your IDX provider does. It's still worth asking a provider how they source data, because it affects how fresh your listings are.
Framed vs. organic IDX: the SEO question
This is the choice that matters most for your website's visibility.
| Framed / iframe IDX | Organic / SEO-friendly IDX | |
|---|---|---|
| Where listings appear | Embedded from the provider's domain | Pages on your own domain |
| Search engine credit | Usually goes to the provider | Can build value for your site |
| Design control | Limited | Much more flexible |
| Setup effort | Lower | Higher |
Organic IDX creates listing and search pages that live on your domain, so they can contribute to your site's search visibility. Framed solutions are simpler but tend to give you less SEO benefit and less design control.
Popular IDX providers to compare
Real estate websites commonly use providers such as IDX Broker, Showcase IDX and iHomefinder, among others. Rather than picking by name, compare them on:
- MLS coverage — does the provider support your specific MLS?
- Search experience — map search, polygon draw, saved searches and alerts.
- Lead capture — registration prompts and how leads are sent to your CRM.
- SEO approach — organic pages on your domain vs. framed content.
- Design flexibility — can it match your brand, or does it look bolted on?
- Total cost — setup, monthly fees and any per-MLS charges.
The best IDX provider is the one your MLS supports, your visitors enjoy using, and your CRM can actually receive leads from.
Connecting IDX leads to your CRM
A search tool that captures registrations is only half the job. The other half is making sure every lead reaches you instantly. A well-built setup sends new IDX registrations straight into a CRM such as GoHighLevel, tags them by search behavior and starts an automated follow-up sequence within minutes.
Quick checklist before you choose
- Confirm your MLS and whether it supports the provider.
- Ask your broker to sign any required IDX agreements early.
- Decide between organic and framed based on your SEO goals.
- Make sure leads route to your CRM, not just an email inbox.
- Test the search experience on your phone — that's where most buyers browse.
Get these right and your property search stops being a feature on your website and starts being the reason people come back to it.
Asraful Islam
Real estate website developer and founder of Reaplex. 200+ real estate websites built, rated 5.0 from 180+ reviews on Fiverr and Upwork.
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