Check whether listing URLs use your domain or the vendor's subdomain. Then ask which pages you'd retain if the relationship ended. Vendor-hosted listing pages often earn real traffic that builds authority for the vendor's domain, not yours — and it doesn't transfer when you switch.
Look at the address bar
This check takes about thirty seconds, and most teams have never done it.
Go to your own site. Click through to a property search, then into an individual listing. Now read the URL.
yourteam.com/listings/123-main-street/ — the page is on your domain. Whatever authority it earns accrues to you.
yourteam.idxvendor.com/listings/... — it's a subdomain of your site, but search engines frequently treat subdomains as separate properties. The relationship is weaker than it looks.
search.yourteam.com or yourteam.vendorplatform.com — same concern, and worth checking which registrar and which DNS actually control it.
vendorplatform.com/agents/yourteam/... — you're a page on someone else's website. Everything that page earns belongs to them.
Then run the same check on your neighborhood pages, your market reports, and your sold-listing archive if you have one. Teams often find the site they thought was theirs is a shell wrapped around a vendor property.
The question that clarifies it
Ask this and the picture resolves fast: if you switched vendors tomorrow, which of these pages would still exist at the same URL?
For anything on the vendor's domain, the answer is none. The pages disappear, the links pointing at them break, and whatever ranking history they accumulated goes with them. You don't get to redirect URLs you don't control.
This is the part that makes it different from ordinary "we use a third-party tool." You aren't renting software. You're building an asset on land you don't own.
Why it's hard to see
Three things make this invisible in normal reporting.
The site looks like yours. The header, the branding, the navigation all match. Visually there's no seam.
Analytics can obscure it. Depending on setup, vendor-hosted pages may report into your property as though they were yours, or may not report at all — and the second case makes the problem look smaller than it is.
Search Console will tell you if you ask correctly. Your property covers your domain. If listing pages live elsewhere, they simply won't appear in your data. Their absence reads as "we don't get much listing traffic" rather than "our listing traffic isn't ours."
That last one is the trap. The finding presents as a content problem, and teams respond by writing more content on the domain that was never the issue.
What the trade-off actually is
This isn't an argument for abandoning IDX. MLS rules, data licensing, and the practical cost of building compliant search yourself are real constraints, and for most teams the vendor arrangement is the right call.
The point is to know what you're trading. If the arrangement puts your highest-traffic pages on a domain you don't control, then the content you do control — neighbourhood guides, market analysis, your team pages, your sold history — carries more weight, not less. Many teams have it backwards: they invest in the listing pages, which are replaceable and not theirs, and neglect the pages that are.
The related check: agent bios versus the team page
While you're in Search Console, search your team name and see which page Google returns. If an individual agent's bio outranks the team page for the team's own name, inbound interest is routing to one person rather than the group. That's usually a linking artifact — bios accumulate more internal links and richer content than the page meant to represent everyone — and it has direct commercial consequences for how leads distribute.
What you can and can't conclude
Verified — Where your listing pages live. It's in the URL and you can read it.
Pending — What the arrangement costs you. Quantifying it means comparing performance of the two domains side by side, which requires access to whatever analytics the vendor provides — and vendors vary enormously in what they'll share. Without that, you know the shape of the problem but not its size.
Directional — That authority built on a vendor domain doesn't transfer. Well-supported by how search engines treat domains and subdomains, but the degree varies by configuration, and anyone quoting you a precise figure is guessing.
What to do this week
Write down every URL pattern on your web presence and mark each one ours or theirs. That single document changes most teams' view of their own site, and it takes an afternoon.
Content living on someone else's domain is one of six symptoms in the full map of how to tell if my website is losing me clients.
More on how we work with realtors and real estate teams.