Contact
The most useful thing you can send is a correction.
Corrections
If the tool produced a number you know to be wrong — you have the actual tax bill, the actual premium, the actual note rate — that is worth more than any amount of guessing on this end. Include the state, what the tool said, and what the real figure is.
Missing occupations
The wage table covers a few hundred job titles and misses plenty. If a title came back unmatched, say which one and it can be added.
Method questions
Most are already answered in how it works, which sets out every formula and dataset. If something there is unclear or looks wrong, that is a bug in the explanation and worth reporting.
What this site cannot help with
It cannot look up who lives at an address, confirm what a particular person earns, pull anyone's credit, or produce anything usable for tenant screening, employment decisions, lending decisions or insurance underwriting. Those uses are prohibited by the terms, and the site holds no data that would support them in any case.
One person reads it. Corrections get answered first; everything else gets answered eventually. Please put the state or the address type in the subject line — it makes the correction far easier to act on.