Is there a free website where I can look up how much a house is worth even if it's not for sale?

In many states and counties, the local assessor's office or department of assessment will have a search function on their website where you can do just that. Often, you'll need the parcel code, but sometimes you can get the info with just the address. For example, check out the Sacramento County search function I linked to below (sorry - Internet Explorer is required).Is there a free website where I can look up how much a house is worth even if it's not for sale?
Lets resolve this overdue question by bringing it to a vote.

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