ATTOM Property API vs HUD open data for AI agents
ATTOM Property API is a REST API for US property records: ownership, sales history, valuations (AVM and rental AVM), mortgages, schools, crime and neighborhood data. 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
- ATTOM Property API: Deep public-record and valuation data on any US property, rather than finding homes currently on the market.
- HUD open data: Mapping subsidized apartment buildings and checking rents against HUD Fair Market Rents, not finding a vacant unit.
Side by side
| ATTOM Property API | HUD open data | |
|---|---|---|
| Searches | Properties by address, parcel number, ATTOM ID or latitude/longitude; the docs describe last sales, sales history and valuations, not active for-sale or rental listings. | Locations and program details of HUD-subsidized multifamily properties; Fair Market Rent figures by area. |
| Returns | JSON or XML property records with characteristics, ownership, sale history, AVM values and area data. | Property locations and assistance-program attributes; FMR rent figures. No vacancy, availability or asking-rent fields are described. |
| Before the first call | A trial sign-up to receive an API key; production plans through ATTOM. | Nothing stated for the ArcGIS endpoint; the Fair Market Rents API needs a HUD USER account and an access token. |
| Free | 30-day free trial with an API key. | – |
| Acting on a result | Nothing: no agent, landlord or listing contact fields are described. | Nothing: no property manager contact is described. |
| Limits on keeping or showing results | Use of data is governed by a separate license agreement that is not published on the site. | – |
| Coverage | US, 160+ million properties. | US |
| MCP server | ATTOM MCP Server (access arranged through ATTOM): https://www.attomdata.com/solutions/delivery/mcp-server/ | – |
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 ATTOM Property API?
A trial sign-up to receive an API key; production plans through ATTOM.
Is ATTOM Property API free?
30-day free trial with an API key.
Sources
Every line about another company comes from its own pages. Prices and terms change, so check the source before you rely on one.
ATTOM Property API, read on October 15, 2026:
- attomdata.com/solutions/property-data-api: “Sign up for a free 30-day trial to receive an API key and explore ATTOM’s extensive property data”
- attomdata.com/solutions/property-data-api: “Covering 160+ million U.S. properties and 99% of the U.S. population”
- attomdata.com/solutions/property-data-api: “ownership information, lat/long, square footage, loan types, sales history, sales comps, crime, schools and more”
- api.developer.attomdata.com/docs: “return information pertaining to the most recent sale of a property or list of properties”
- attomdata.com/solutions/property-data-api: “The ATTOM MCP Server provides AI-native access to ATTOM Intelligence through the Model Context Protocol (MCP).”
- attomdata.com/solutions/delivery/mcp-server/how-it-works: “Access is governed, permissioned, and centrally managed”
- attomdata.com/terms-of-use: “subject to the terms of a separate license agreement”
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.”