I've been flipping with family around King County and got tired of rebuilding the same spreadsheet for every property, so I built a tool for it: flipitnw.com

You enter a King County address and it pulls the county's parcel data and nearby recorded sales, estimates the renovation budget, and gives you a projected profit, a safe max offer, and a green/yellow/red verdict. You can compare up to 10 homes side by side.

I also added a zoning and site check, since that's been a real blind spot on our deals. It shows the lot's zoning, what Washington's new laws require the city to allow (for example at least 4 homes per lot in Seattle, Bellevue, Kent and the other big cities, plus 2 ADUs), and whether King County maps show steep slopes, wetlands, streams or flood zones on or near the lot.

The calculator and a one-page summary are free, no sign-up. The full lender/contractor packet and the 10-home comparison are paid.