RESO Web API vs RETS: What Changed and Why Your Plugin Broke

The short version of RESO Web API vs RETS: RETS is the old way MLS listing data moved, it has been frozen for years, and boards are switching it off. The RESO Web API replaced it, and it is now mandated for REALTOR-operated MLSs. If your property search stopped updating, this is usually why.

You do not need to understand the protocols to make the right decision here. You need to know which one your MLS runs, whether your plugin supports it, and what it costs you if it does not.

What is the difference between RESO Web API vs RETS?

Both are ways of getting listing data out of an MLS and onto your website. RETS came first, in the early 2000s, and worked by downloading large batches of records on a schedule. The RESO Web API is the modern replacement, built on OData v4, RESTful HTTP, JSON and OAuth 2.0 — the same plumbing the rest of the web already uses.

The last row matters more than it looks. Under RETS, every MLS named its fields differently, so a plugin built for one board often needed rework for another. Standardised fields are the reason the newer standard is cheaper for vendors to support — and why support for the old one is disappearing.

Why did your IDX plugin suddenly stop working?

Almost always because one side of the connection was retired while the other was not updated. Three versions of the same story:

• Your MLS switched off its RETS server. Boards are doing this on their own timelines, often with a notice most agents never read.
• Your vendor dropped RETS support. Realtyna, for instance, ended all RETS integrations on 31 December 2024. A plugin that only speaks RETS has nothing to talk to.
• Your plugin was never updated. The feed moved; the software did not. Common with abandoned or heavily discounted plugins.

The symptom is usually not a dramatic error. It is listings quietly going stale — sold properties lingering, new ones never appearing — which is why it often runs for weeks before anyone notices.

Is RETS actually dead?

Effectively, yes, though not everywhere at once. The transition has been rolling since 2018 and is expected to be substantially complete by 2027. More than 500 MLSs worldwide were certified on the Web API as of mid-2026.

So the practical position in the RESO Web API vs RETS question is no longer a choice. For any new integration, the Web API is the answer. RETS is only relevant if your specific board has not finished migrating — and even then it is a temporary arrangement with a known end date.

RESO Web API vs RETS: which one does your MLS run?

Three routes, quickest first.

1. Ask your MLS directly. “Have you completed the Web API transition, and is RETS still available?” One email settles it.
2. Check RESO’s transition status. Boards that have completed the move are published, and if yours appears there, RETS access has probably already been retired.
3. Ask your IDX vendor which standard your feed uses. They will know immediately. If they cannot answer, that itself is informative.

What should you do about RESO Web API vs RETS now?

If your listings are updating correctly, nothing urgent. If they are not, work through this in order before spending money.

1. Confirm the feed is actually broken rather than slow. Compare three or four listings on your site against the MLS.
2. Check your vendor’s status page and email. Retirement notices are usually sent, and usually ignored.
3. Ask whether your plan supports the Web API. Many vendors support both; moving may be a settings change rather than a migration.
4. Only then consider changing vendor, and check first that the new one has an active feed with your board.

Step four is where money gets wasted. Vendor coverage is per-MLS, and a provider with excellent reviews elsewhere may have no connection to your board at all — the subject of choosing an IDX provider by MLS rather than by feature list.

Does the RESO Web API vs RETS switch cost you anything?

Usually less than people fear, and occasionally nothing at all. If your vendor supports both, moving your feed across is typically a reconfiguration they perform. Where costs appear:

One genuine upside: Web API integrations are cheaper to build than the RETS equivalents were, because the data arrives clean and standardised. If you are commissioning new work, you are buying at a better moment than agents did five years ago. The full breakdown is in what IDX actually costs.

RESO Web API vs RETS, side by side

Both are ways of moving MLS data from the board to your website. One was designed in 1999 and one in the 2010s, and almost every practical difference follows from that twenty-year gap.

Read the last row first. The RESO Web API vs RETS debate is largely settled in practice — boards are retiring the old standard on their own schedules, and the only real question left is when yours does it.

The standardised field naming in row five matters more than it looks. Under RETS every board invented its own names for the same things, which is why vendors charged per board and why adding a second MLS was disproportionately expensive.

What RESO Web API vs RETS means for your website

For most agents, very little day to day — right up until it means everything for a week. These are the four practical consequences.

• Listings update faster. On-demand queries mean a price change can appear in minutes rather than at the next scheduled pull.
• More fields are available. Open house times, virtual tour links and richer photo data are more consistently exposed.
• Vendors can support more boards. Standardised naming is why multi-board coverage has improved and why the RESO Web API vs RETS shift quietly reduced some prices.
• Old plugins stop working. Anything built purely for RETS eventually dies when the board switches, with little warning.

That last point is the one that reaches you. Most agents first encounter the RESO Web API vs RETS question on the morning their listings disappear, which is the worst possible time to learn about it.

RESO Web API vs RETS: how to tell which one you are on

Three routes, in order of speed. You do not need technical knowledge for any of them.

1. Email your IDX vendor and ask plainly: is my feed on the RESO Web API or RETS, and what is the migration plan? A one-line question with a one-line answer.
2. Ask your MLS, who will also tell you their retirement date for the old standard if one is set.
3. Check your plugin’s settings screen. Many name the standard directly, and an old plugin with no Web API option answers the RESO Web API vs RETS question by omission.

Do this before you need to. An agent who knows their board’s retirement date has months to plan; an agent who does not finds out when the listings vanish.

What a RESO Web API vs RETS migration actually involves

Less than agents fear, and it is mostly waiting. Moving across the RESO Web API vs RETS divide is a vendor-side change; your website design, content and URLs stay exactly as they are.

Two to three weeks, most of it board review. Crucially, listing URLs usually stay the same, so a RESO Web API vs RETS migration does not normally cost you search visibility the way a platform move can.

Who pays for the RESO Web API vs RETS migration?

Ask before you need the answer, because it varies and it is negotiable. Some vendors treat re-establishing a feed as routine maintenance; others bill it as a new setup.

• Included, no charge. The better vendors treat the RESO Web API vs RETS transition as their problem, because it is their product that broke.
• A setup fee, typically $0–$300. Common, and worth asking to have waived given you did not choose the change.
• A forced upgrade to a higher tier. Push back. If your board changed standards, that is not a reason for your monthly cost to rise permanently.

Get the answer in writing now, while nothing is broken. Negotiating a RESO Web API vs RETS migration fee is much easier when your listings are still live than when they have been down for a week.

Warning signs your feed is on borrowed time

Feeds rarely fail without notice; the notice is just easy to miss. These five symptoms usually appear weeks before an old feed stops entirely, and each is a prompt to ask the RESO Web API vs RETS question now rather than later.

• Listings lag further behind than they used to. A sold property staying live for a day is a scheduling problem, and scheduled pulls are a RETS-era design.
• New fields never appear. If competitors show open house times and virtual tours and you cannot, your feed is probably older than theirs.
• Your plugin has not been updated in a year. Abandoned IDX plugins are the most common casualty of the RESO Web API vs RETS transition.
• Your board has emailed about “data access changes”. These notices are dull and easily deleted, and they are the warning.
• Intermittent gaps. Listings vanishing and returning suggests a connection being maintained on one side only.

Any two of those together justify an email to your vendor this week. The cost of asking early is one message; the cost of asking late is an outage in your selling season.

What to do if your listings are already down

Work through this in order. Most outages blamed on the RESO Web API vs RETS changeover turn out to be lapsed credentials or an expired agreement, both of which are same-day fixes — the full list is in the six most common causes of a feed that will not sync.

1. Check your MLS membership and IDX agreement are current. An unpaid invoice suspends the feed with no other symptom.
2. Ask the vendor for the last successful sync time. This tells you when the problem actually started.
3. Ask directly whether the board has changed standards. Vendors do not always volunteer it.
4. Put a holding message on the search page so visitors see an explanation rather than an empty result.
5. Get a written timeline. If reconnection will take two weeks, you want that in an email, not on a call.

Step four matters more than it seems. An empty listings page looks broken and costs you credibility; a short note saying listings are updating restores it for almost no effort.

And if the answer does turn out to be the RESO Web API vs RETS changeover, treat it as a prompt to review the vendor as well as the feed. A provider who let a known, scheduled industry migration take your site offline without warning has told you something useful about how they operate.

Why RESO Web API vs RETS matters more for small agents

A large brokerage has staff who read board notices and a vendor relationship with someone answering the phone. A solo agent has neither, which is why the RESO Web API vs RETS transition tends to land hardest on exactly the people least equipped to absorb it.

There is also a cost angle. Standardised field naming makes it cheaper for vendors to support additional boards, and some of that saving has reached agents in the form of lower multi-board pricing. If you pay for two feeds on old infrastructure, the RESO Web API vs RETS move is a reasonable moment to ask whether a single modern feed now covers both.

The practical takeaway is unglamorous: put a reminder in your calendar once a year to email your vendor and your board with the same two questions. Which standard is my feed on, and when does the old one retire here? Two minutes annually removes almost all the risk described on this page.

Frequently asked questions

Will my listings look different after the switch?

They should not. The standard governs how data reaches your site, not how it is displayed. What usually improves is freshness, because the Web API supports faster updates than batch downloads. Occasionally a field your old setup displayed is named differently and needs remapping.

Can I connect directly to my MLS instead of using a vendor?

Technically yes, if your MLS issues direct credentials and you have a developer. In practice most agents should not. You take on compliance, uptime and field mapping yourself, and the saving rarely justifies it unless you are running something unusual.

My MLS still offers RETS. Should I stay on it?

Only if moving is genuinely disruptive right now. RETS is frozen and your board will retire it eventually, so anything you build on it has a shelf life. If you are making a change anyway, make it once and make it to the Web API.

How long does re-establishing a feed take?

Plan for one to three weeks. The technical work is quick; waiting on the MLS is not. New feed requests go through the same approval process as a first-time application, which runs from a few days to a fortnight depending on the board’s workload.

Is RETS actually going away everywhere?

Effectively yes, though not on a single national date. Boards retire it individually, so the RESO Web API vs RETS timeline depends entirely on your MLS. Ask yours for its date and diarise it.

Will my listing pages change appearance?

Usually not. The standard governs how data arrives, not how your site displays it. You may gain fields you did not have before, such as open house times, but the layout and URLs stay as they were.

Should I switch before my board forces it?

If your vendor supports it, yes. Moving on your own schedule takes two to three weeks with listings still live; moving after a shutdown means an outage first. The RESO Web API vs RETS switch is far less painful when it is planned.

The bottom line

RESO Web API vs RETS is a settled question everywhere except the boards still finishing their migration. If your search has gone stale, check the feed standard before you blame the website — and before anyone sells you a rebuild you may not need.

Ask your MLS one question and your vendor one question. Between them you will know exactly where you stand.

Written by

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.

More about me →