I am looking to access an online database of real estate information (e.g. tax information and sales history for a particular address, lot size, square footage, BPOs, etc.).
Companies such as RealQuest offer reports as a subscription service, but I'm looking to download the raw data, preferably in XML format (I don't want to parse the output since the presentation could change without notice).
Are there any such services available?
I know Trulia is rolling out an api option, however I don't think you'll have any control over the presentation.
You may be able to pull information from google base. A lot of the major places pull data from google base to feed real estate scripts. There's even a wordpress plugin that does this. It pulls real estate information for anything within a certain area.
I design a lot of real estate sites, and the issue is that there is no standard for information across real estate or property databases (MLS systems or real estate tax information systems).
Additionally, MLS systems are protective of their data. So you would need to check with each individual MLS board to see if there is an ability to access their RETS or IDX feed without being a broker.
If you are looking to provide this information in a certain area, you may check with that area's property valuation department. A lot of them use similar systems, such as visionappraisal.com, which may have an api that you can use.
Unfortunately, unless you have access to a major player in the real estate data department, it becomes very difficult to have access at the level of which you are describing.
But, I wish you the best of luck!