Public ArcGIS MapServer endpoint for St. Louis County parcel data. URL, supported fields, and a working sample query — copy it, or open it directly in the UrbanKit parcel lookup tool.
https://maps.stlouisco.com/hosting/rest/services/Maps/AGS_Parcels/MapServer/0/query?where=UPPER(OWNER_NAME) LIKE UPPER('%SMITH%')&outFields=LOCATOR,OWNER_NAME,PROP_ADD&returnGeometry=false&f=json&resultRecordCount=10Open this URL in a browser tab to see the raw ArcGIS JSON response.
| Field name | Label | Searchable |
|---|---|---|
| LOCATOR | Parcel Locator Number | YES |
| PARENT_LOC | Parent Locator | YES |
| OWNER_NAME | Owner Name | YES |
| OWN_ADD | Owner Address | YES |
| OWN_CITY | Owner City | YES |
| OWN_STATE | Owner State | YES |
| OWN_ZIP | Owner ZIP | YES |
| PROP_ADD | Property Address | YES |
| PROP_ZIP | Property ZIP | YES |
| PROPCLASS | Property Class | NO |
St. Louis County MO (St. Louis metro west/south, county seat Clayton — NOT the independent City of St. Louis) provides AGS_Parcels/MapServer/0 with 30+ fields: LOCATOR (parcel ID), PARENT_LOC, TAXYR, OWNER_NAME, PROP_ADRNUM, PROP_ADD, PROP_ZIP, OWN_ADD, OWN_CITY, OWN_STATE, OWN_ZIP, SCHSUB (school subdivision), MUNYCODE (municipality code), TAXCODE, ASSTIMPVAL, TOTASSMT, APPLANDVAL, APPIMPVAL, TOTAPVAL, PROPCLASS, LUC, LANDUSE2, LUCODE, TENURE, BLDGNAME, TWPNAME. Query confirmed live: UPPER(OWNER_NAME) LIKE '%SMITH%' returns real results (e.g., 'SMITH KIMBERLY & ANTHONY T/E' at '11041 LILAC AVE'). St. Louis County MO (FIPS 29189) is a separate entity from the City of St. Louis (FIPS 29510, an independent city not part of any county). The GeoData portal at data-stlcogis.opendata.arcgis.com provides open data downloads and GeoServices API links. The maps.stlouisco.com server is the live REST host.
St. Louis County Geospatial Data Center — https://gis.stlouiscountymo.gov/
/query?where=…&outFields=*&f=jsonto the URL. The sample query above is a working example you can paste into a browser tab to see the raw JSON response.Counties publish parcel data through their own ArcGIS Server installations, each with its own schema. One county uses APN, another uses PIN, a third uses PARCEL_ID. Some expose owner names; others keep them on a separate assessor's portal. The searchable fields list above reflects what this county actually publishes — not what you might expect from a national standard (there isn't one).
For background, see What is an APN?
Many county servers allow public reads but block browser cross-origin requests. The UrbanKit parcel lookup tool fetches directly from your browser; if it works there, the layer is technically public. For your own integration, you may need a same-origin proxy or server-side fetch.
Possibly — counties move services without warning. We re-verify entries weekly and flag stale ones. If you're seeing a fresh 404, please let us know and we'll update the listing.
Most are. Public ArcGIS layers don't typically rate-limit individual reads, but heavy programmatic use can trigger throttling at the host level. Be respectful — query what you need.