Warning: Riverside county do not have a online parcel owner checking tool. Since 2022 Riverside County do not allow public to view or download parcel owner shapefile (file geodatabase) any more. Current the only way to get parcel owner is to ask County assessor office (GIS team). They can email you download link for free. You can sign up a contract as purchase order (around $150/months) to get parcel owner monthly. Riverside county update parcel owner monthly. San Bernadio County update parcel owner bi-weekly.
San Bernadio County have 2 online parcel owner checking tool. One is on enterprise portal, one is on arcgis online open data.
This is web app builder app on SB county enterprise portal
Step 1. Click parcel to see the owner
https://arcpropertyinfo.sbcounty.gov/
Step 2. Parcel owner comes from here
https://arcportal.sbcounty.gov/arcgis/rest/services
https://transparentgov.net/json2tree/esri/server/folder.html?org=https%3A%2F%2Farcportal.sbcounty.gov%2Farcgis%2Frest%2Fservices&url=https%3A%2F%2Farcportal.sbcounty.gov%2Farcgis%2Frest%2Fservices&arcgis_online_token=&select_folder=10&select_layer=0
Step 3. Check the parcel owner on google maps
https://transparentgov.net:3200/googlemaps/default?layer_id=0&layer=Report¢er_lat=34.083940495317705¢er_long=-117.62311385998551¢er_zoom=19&url=https%3A%2F%2Farcportal.sbcounty.gov%2Farcgis%2Frest%2Fservices%2FPAT_Public%2FSBC_PAT_Public_Report%2FMapServer&overlayType=overlayType_image&panto=0
Step 4. click google street view to check this property condition
more info https://arc.sbcounty.gov/property-information/