How we work

Sources

Every permit in the dataset was issued by a city or county building department in the United States, and every permit links back to that office's own record, so you can always check the original. Some offices send us their records directly; the page for governments explains how that works.

Freshness

New permits arrive every day, and most connected offices are refreshed at least once a day. How soon a permit appears depends on when its office releases it. Coverage figures on this site carry an "as of" date.

How we collect

Our crawler identifies itself as a research bot, follows each site's robots.txt and keeps its load low. It never gets around logins, CAPTCHAs or other access controls; where an office uses them, we ask for the records instead.

If our crawler causes a problem for your site, write to [email protected] and we will slow it down or stop. Site administrators can find more on the page for governments.

What varies

Coverage and the details on each permit vary from office to office. The map on the home page shows where we are today.

Corrections

If a record looks wrong, tell us the issuing office, the permit number and which detail you think is off by writing to [email protected]. A link to the office's record helps us find it quickly. See corrections and removal.