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 call center routing system by region
An agent who knows the local regulatory quirks and typical claim patterns of one region handles a call from that region faster and better than an equally skilled agent who has never worked a claim from there before, and an insurance company running a national call center realized its "route to next available agent" system was ignoring that entirely, treating every agent as interchangeable regardless of which region a caller was in.
For calls coming through the company's web-based contact form and callback request system, rather than a traditional phone line, the caller's IP address was already part of every request. /v1/ip resolved that address into region and city, which the routing system used to match a caller against agents who had been assigned specialization in that particular region, rather than routing purely by who happened to be free first.
This did not replace availability as a factor entirely, since a perfectly matched agent who is unavailable for another twenty minutes is often a worse outcome than an available agent with general knowledge, so the routing logic weighed both together: a strong regional match with a short wait beat a mismatch with no wait at all only up to a point, tuned based on actual wait time data the company gathered once the new system was live.
The company also used the same regional data to route certain calls to agents fluent in a relevant local language variant, not just a broad language category, since a general "Spanish-speaking agent" pool served callers less well than one that accounted for regional differences in terminology that come up specifically in insurance and claims conversations, a detail that mattered more to caller satisfaction scores than the company had initially expected going in.
None of this required a phone system overhaul. The location resolution happened at the point where a caller's contact request first reached the company's servers, before it was ever handed off to the call routing logic itself, which only needed a region field to make its decision, a small integration point rather than a rebuild of the routing system as a whole.
The company treated the detected region as a strong signal rather than an absolute fact, aware that a caller on a corporate VPN or traveling could resolve to a region other than where they actually held their policy. For cases where policy region and detected region disagreed, the system fell back to matching against the caller's policy record instead, treating the IP-based detection as useful primarily for the more common case where policy holders are also physically in the region their policy covers, calling from a normal home or mobile connection.
Volume tracked inbound contact form submissions, a workload well inside the free daily allowance for a company of this size, since the lookup ran once per contact request rather than continuously during a call. The change did not require new headcount or new agent training beyond formalizing which agents already had strength in which regions, an inventory the company had informally but had never systematically used for routing before.
Documentation for the endpoint is at /docs/ipv4-lookup/ and /docs/ipv6-lookup/.