Check your own lot: a parcel-level ADU screen for King County (beta)

Type a King County address and the site now looks up your actual parcel in the county's records, works out which city it sits in, pulls that city's zoning for the exact point, and applies the ADU rules we have verified against municipal code — with every answer citing the section it came from. Seattle, Bellevue, and Kirkland are wired in so far. It is a planning-level screen, not a permit determination, and it is built to say so: where a rule depends on a fact King County does not publish, it tells you which fact is missing instead of guessing. Whether your lot backs onto an alley is the clearest example — in Seattle that is the difference between a five-foot rear setback and none at all, and no county dataset records it. Before publishing we ran twenty real residential parcels through the whole chain and checked every answer against a second, independent source: the jurisdiction against the geocoder, the lot size against a separate county table, the zone against the assessor's own record. Agreement was 100%. The full method and every known limitation are written up at /methodology and in the repository.