In the U.S., in any arbitrary state and county (subject to availability — see diagram and description), I want to:

start with:

  • state
  • county
  • APN (Assessor's Parcel Number)

and return:

  • a physical street address (preferred)
  • or latitude longitude coordinates.

Is there a free way to do this on the internet?

Maybe a big-data or open source project or API perhaps? Don't worry about all data being available. Coverage areas similar to the following diagram are expected and accepted.

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  • 2
    Are you concerned with a single county or many? If many, then you will probably not find much to do this for free. There is a large discrepancy between what counties store, how they store it, and who they will provide that data to. Some counties don't even have parcel information electronically. Dec 28, 2015 at 13:15
  • @EvilGenius: Agreed. I was hoping to find maybe an open source project that is underway or attempting to solve this challenge? Or maybe some projects only serve a subset of counties but have begun to assemble a centralized, standardized database?
    – Mowzer
    Dec 28, 2015 at 13:47
  • 3
    @Mowzer as a former Address Coordinator for the city I work for and live in I have to tell you that this would not only be a challenge but it would be a dream-come-true if it ever happened. Not only do some counties NOT have their addresses organized but some (like ours) reassign parcel numbers arbitrarily. That's right. if Parcel #12345 is split, the parcel # for both side might include #12345 or they might not. AND #12345 might be used later for an almost completely unrelated parcel. An Address database needs to be developed that is tied to a national street database. That's the only answer. Dec 28, 2015 at 13:58

1 Answer 1


As others have stated, not all counties have this data available electronically. Others have it available but will either charge for the data or not make it available to the public at all. Not all counties use the same format or name of data: (APN vs GPIN vs TIN) and merging the data for multiple counties within one state can become a nightmare (data storage format mismatches, formatting mismatches, etc). In addition, any research that involves a legal aspect or survey grade data (property owner, tax information, etc) is required to pull property records from courthouse or assessor's offices because digital feeds can be incorrect or out of date.

Because of the data inconsistencies, it would be tough to create the logic to do a reverse address lookup based on a parcel number. In addition, every county/independent city is going to be continuously updating their data, so as soon as you received a complete package and formatted it to what you would need to query it, it would be out of date.

Links to two commonly used parcel data feeds are below, however, they are pay sites.


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