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.
Verifying a rental property's address for a listing site
A guest arriving at a vacation rental to find the pin on the map pointing at an empty lot, a different building entirely, or a location a few streets away from the actual property is a bad experience that reflects on the platform as much as on the host, and a vacation rental platform allowing self-service listing creation found this happening often enough that it warranted a real fix rather than relying on guest complaints to catch bad addresses after the fact.
Most cases were not deliberate fraud. Hosts entering an address by hand made ordinary typos, dropped a pin slightly off from the actual property while setting up a new listing, or entered a postal code that did not match the city and street they had typed elsewhere on the same form. A smaller number of cases did look more deliberate, addresses that resolved somewhere entirely different from what was claimed, sometimes tied to other signals suggesting a listing was not what it claimed to be at all.
The platform added a verification step to the listing creation flow. The address a host entered went to /v1/forward, which reported a match along with an indication of how confidently it resolved, and the platform compared that resolved location against the pin the host had separately dropped on a map during setup, flagging listings where the two disagreed by more than a small tolerance, a strong signal that either the typed address or the dropped pin was wrong, since a genuinely accurate listing should have both agree closely. The postal code entered was separately checked against /v1/postcode to catch cases where it did not correspond to the city also entered on the form.
Listings that passed both checks published normally. Listings with a mismatch between the typed address and the dropped pin, or a postal code inconsistent with the rest of the entered address, were held for a quick manual review, or in some cases sent back to the host with a specific prompt to double check and correct the flagged field before the listing could go live, catching the error at the moment it was easiest and cheapest to fix, before a guest had booked and traveled based on it.
The platform was clear internally that this verification confirmed an address was well-formed and consistent with the pin location, not that the property itself matched its photos or description in any other respect, a separate part of its trust and safety process that the address check did not attempt to solve. Treating the address check as one narrow, well-defined piece of a broader trust system, rather than asking it to do more than it reasonably could, kept expectations realistic both internally and in how the feature was described to hosts.
Volume tracked new listing creation and edits to existing listing addresses, a modest and predictable workload relative to the platform's total booking volume, comfortably inside the free daily allowance for a platform of moderate size.
Documentation for both endpoints is at /docs/forward-geocoding/ and /docs/postal-code-lookup/.