5 posts tagged with "Project motivation"

You need to turn an address into a coordinate. That's the whole ask. The problem is that the two ways to get there both start as a project.

Rent an API and the address is now someone else's business. Every lookup is a billable request and a row of your users' home addresses leaving your infrastructure, and the free tier caps out at one request a second, so a table of any size takes days. Self-host Nominatim instead and you've signed up for PostgreSQL, an osm2pgsql import measured in hours and tens of gigabytes, and a service you run on a box you can never embed inside your own app. Either way, the thing you wanted — geocode(address) — sits on the far side of a week of setup.

You've got a hundred thousand addresses to reconcile. Two databases, the same clinics and providers scattered across both, each one spelled a dozen ways: abbreviated here, reordered there, a postcode dropped, a suite number glued to the street. You run them through a geocoder, match on the resolved coordinate, and it works. Mostly. Some fraction land on the wrong building, the wrong block, the wrong town, and the geocoder won't tell you which fraction. It hands back a pin for every row and the same silent confidence for all of them: none.

That's the gap we set out to close. Every geocoder chases accuracy, be-right-more-often, and so do we. The piece almost nobody hands you is the one underneath it: a number on each answer that tells you which ones to trust, so you can keep the good ones and send the rest to a human.

Open the demo, open your browser's network tab, and type an address. You'll watch it resolve to a rooftop coordinate — 1600 Pennsylvania Ave lands on the actual building, within about ten metres — and then you'll notice what's missing from the network tab: a request carrying your address. There isn't one. The parser ran in the page. The gazetteer it resolved against is a file on a CDN that the page read a few kilobytes at a time. The query never left your machine.

That's the pitch, and it's worth being clear about why it's unusual, because the three things the rest of the market hands you each ask you to give something up.

Every geocoder turns an address into a coordinate. Almost none of them will tell you where that coordinate came from. You get a latitude, a longitude, and a vague confidence enum, and when it's wrong you have no thread to pull — no way to know whether the point came from a federal data release, a county GIS office, or a straight line drawn down the middle of a street. Mailwoman keeps the source on every point. Here's New York, every dot colored by the open dataset it came from.

You have a pile of records and no key to join them on. A clinic shows up in the federal provider registry, again in a state licensing export, a third time in a funding-program spreadsheet somebody keyed by hand. None of those files share an identifier. The provider number is internal to one publisher, the facility ID to another. So the join you actually want — which of these are the same place — isn't a join at all. It's a judgment call, repeated a few million times.

The market hands you two tools for this, and each one solves a different half of the problem. Neither one finishes.