SimplyRETS vs HUD open data for AI agents
SimplyRETS is a developer API and WordPress plugin that turns your own MLS's RETS or RESO Web API feed into a simple REST listings API. HUD open data is a set of government datasets about HUD-subsidized multifamily properties (an ArcGIS feature service) and Fair Market Rents (HUD USER API); not a listings API.
The short answer
- SimplyRETS: An affordable, simple REST layer for an agent or brokerage that already has its own MLS data feed.
- HUD open data: Mapping subsidized apartment buildings and checking rents against HUD Fair Market Rents, not finding a vacant unit.
Side by side
| SimplyRETS | HUD open data | |
|---|---|---|
| Searches | Listings from the MLS feeds you connect: active, under contract, pending and closed; residential, condo, rental, multifamily, commercial and land, plus open houses. | Locations and program details of HUD-subsidized multifamily properties; Fair Market Rent figures by area. |
| Returns | Listing records with property details, photos, and listing agent and office information when the MLS feed supplies it. | Property locations and assistance-program attributes; FMR rent figures. No vacancy, availability or asking-rent fields are described. |
| Before the first call | RETS or RESO Web API credentials from your MLS; whether you must be an agent or broker depends on the MLS. | Nothing stated for the ArcGIS endpoint; the Fair Market Rents API needs a HUD USER account and an access token. |
| Free | Free demo API keys with sample data; no free trial with live data. | – |
| Paid | Basic plan $49 a month, plus a one-time $99 fee per MLS connection. | – |
| Acting on a result | Listing agent and office contact details come with each listing when the MLS feed has them, and some MLSs require showing them. | Nothing: no property manager contact is described. |
| Limits on keeping or showing results | Only listings flagged for IDX display are served, and you must follow the display rules (e.g. last-updated disclaimers) set by your MLS. | – |
| Coverage | Whatever MLS you connect (US); no fixed national coverage. | US |
| MCP server | No official server listed | – |
Where Openpath fits
Openpath has no homes listed yet. Owners and landlords can list a home for rent or sale on Openpath today, free, and agents will find it through the same search as jobs and businesses. Get listed.
Questions people ask
What do I need before I can use SimplyRETS?
RETS or RESO Web API credentials from your MLS; whether you must be an agent or broker depends on the MLS.
Is SimplyRETS free?
Free demo API keys with sample data; no free trial with live data.
Sources
Every line about another company comes from its own pages. Prices and terms change, so check the source before you rely on one.
SimplyRETS, read on October 15, 2026:
- simplyrets.com: “These are our demo API keys, you can use them!”
- simplyrets.com: “Each RETS or RESO Web API connection requires one time $99 connection fee.”
- simplyrets.com: “Get RETS or RESO Web API credentials from your MLS”
- simplyrets.com/faq: “This is dependent on the MLS area you want to connect to.”
- docs.simplyrets.com/topics/fields-and-features-for-idx-compliance: “In some cases it may be required that you show the contact information for the listing agent and/or listing office.”
- docs.simplyrets.com/topics/fields-and-features-for-idx-compliance: “in many areas it’s required to show the timestamp of when the data was last updated in a disclaimer.”
- simplyrets.com: “Basic $ 49 /mo”
- simplyrets.com/faq: “We don't currently offer a free trial period with live data”
HUD open data, read on October 15, 2026:
- catalog.data.gov/dataset/multifamily-properties-assisted: “This dataset denotes HUD subsidized Multifamily Housing properties excluding insured hospitals with active loans.”