Verifying an address matches its stated postal code before checkout
A mismatched postal code and city on an order form looks like a small typo until it turns into a delivery sent to the wrong part of the country entirely.
Building a ride-share pickup radius check
A small ride-share service operating under a campus and surrounding neighborhood agreement had one hard rule it could not break: pickups and drop-offs had to stay inside a defined operating area, agreed with the local authority that had approved the service in the first place. Drivers dropping outside that boundary, even by a short distance, put the whole operating agreement at risk, and relying on drivers to eyeball a boundary on a paper map was never going to be reliable.
The service built the check around coordinates rather than addresses, since a rider's pickup pin was already a coordinate dropped on a map inside the app, not typed text. For that raw coordinate, the service used /v1/reverse to get back a readable address and its administrative area, useful for showing the rider a confirmed pickup location and for staff reviewing any flagged trip after the fact, since a coordinate alone is hard for a human to sanity check quickly, while a resolved address is not.
The actual boundary check itself was a straightforward geometry comparison, run by the app's own backend, between the rider's coordinate and the polygon describing the approved operating area, a calculation that does not require an external service once you have a coordinate to test. Where the location endpoints came in was making sure that test always had a real coordinate to work with, converting whatever a rider had typed into their side of the app, if they typed an address rather than dropping a pin, into a coordinate through /v1/forward first.
A pickup request that fell inside the boundary proceeded normally. One that fell outside it, even slightly, was declined before a driver was ever dispatched, with a message explaining the service could not legally operate outside its approved zone, rather than a driver arriving and then discovering they were not allowed to make the pickup. Declining early saved both the driver's time and the rider's, and it kept a clean record showing the service was actively enforcing its own boundary rather than only discovering violations after the fact.
The service also used the reverse geocoded address on flagged or disputed trips, since a small number of pickups landed right at the boundary edge and needed a human to confirm whether a request had, in fact, fallen inside or outside the approved area, something much easier to judge from a resolved street address and neighborhood name than from a raw pair of coordinates on an internal dashboard.
This kind of boundary enforcement is not a complicated technical problem once the location pieces are in place. The hard part was making sure every pickup and drop-off, however it was entered into the app, always ended up as a coordinate the backend's geometry check could actually use, and that fell to /v1/forward and /v1/reverse working together depending on which direction the data came from.
Volume was tied directly to ride volume, one or two lookups per trip, a workload that stayed inside the free daily allowance for a service of this size operating in a single limited area. Documentation for both endpoints is at /docs/forward-geocoding/ and /docs/reverse-geocoding/.