When I launched carwashin.co.uk , I thought I was building a fairly straightforward local directory product. The problem space was simple: help users find car wash businesses in the UK make browsing easier by city and location reduce the friction of searching generic maps and messy directories That part worked. But then a different type of user question started showing up: “Can I quickly check whether this car wash phone number looks valid before I call it?” That question turned into a second project: whocallme.co.uk . This post is about why I built it, what data I used, what I deliberately didn’t try to do, and why I think there’s room for practical lookup utilities built on top of official public data. The product idea came from a verification gap Directories solve discovery. But for a lot of local-service use cases, users also want verification . Finding a listing is one thing. Deciding whether to trust the phone number attached to it is another.…