Public ArcGIS MapServer endpoint for Cook County parcel data. URL, supported fields, and a working sample query — copy it, or open it directly in the UrbanKit parcel lookup tool.
https://gis12.cookcountyil.gov/traditional/rest/services/CookViewer3Parcels/MapServer/0PIN1010-digit Property Index NumberPIN14_dash14-digit PIN (XX-XX-XXX-XXX-XXXX)street_addressStreet Addresscurl -s 'https://gis12.cookcountyil.gov/traditional/rest/services/CookViewer3Parcels/MapServer/0/query?where=PIN14_dash%3D%2717-09-128-001-0000%27&outFields=PIN10,PIN14_dash,street_address&returnGeometry=false&f=json'
https://gis12.cookcountyil.gov/traditional/rest/services/CookViewer3Parcels/MapServer/0/query?where=PIN14_dash='17-09-128-001-0000'&outFields=PIN10,PIN14_dash,street_address&returnGeometry=false&f=jsonOpen this URL in a browser tab to see the raw ArcGIS JSON response.
| Field name | Label | Searchable |
|---|---|---|
| PIN10 | 10-digit Property Index Number | YES |
| PIN14_dash | 14-digit PIN (XX-XX-XXX-XXX-XXXX) | YES |
| street_address | Street Address | YES |
Cook County uses the 14-digit PIN format (XX-XX-XXX-XXX-XXXX) — exposed as PIN14_dash on this layer. The legacy cookVwHosted/Cook_County_Parcels/FeatureServer was retired in 2026; the active replacement is CookViewer3Parcels/MapServer/0 (1.86M+ parcels). Public fields are geometry, PIN10, PIN14_dash, and street_address only — owner name is NOT on this layer. For ownership lookups, use the Cook County Property Tax Portal at cookcountypropertyinfo.com, keyed by PIN. Cook County reassesses on a triennial cycle divided into three geographic triads: the City of Chicago triad, the north suburban triad, and the south/west suburban triad — each triad goes through a full reassessment every three years on a rotating schedule (north triad reassessed 2025, south/west triad 2026). The county has 5.2M+ residents and 1.86M taxable parcels — the largest county in Illinois by both metrics. The Assessor's office is the valuation authority; the Treasurer's office (cookcountytreasurer.com) handles tax payment records.
Cook County GIS Department — https://www.cookcountyil.gov/agency/geographic-information-systems-gis
Cook County's Parcels layer exposes parcel identifiers (10-digit Property Index Number, 14-digit PIN (XX-XX-XXX-XXX-XXXX)) and address fields (Street Address). Use it for address-to-PIN lookups and identifier queries. All 3 listed fields accept queries. Served as an ArcGIS MapServer layer, which supports query operations but not write operations; last verified 2026-05-15.
/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 Cook 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.