At a 30,000ft view, the site works by building an in-memory routing table at boot time that has an entry for every route on the internet and which ASN (autonomous system number) announces it. From there, it stitches together data on the organization that the ASN belongs to, and geolocation data, and then exposes it in the API/UI. Under the hood it's using a treebitmap[1] data structure, which means that it can do _very_ fast lookups when given a particular ip address or ip address range.
Zooming in a little more, the main data source is MRT dumps from the RIPE RIS project[2]. There are a number of routers that RIPE (one of the 5 regional internet registries that hand out ASNs and IPs) that rely on network operators to share their view of every route on the internet. These routers are probably some of the most well-connected routers in the world. For the purposes of this service, MRT dumps are effectively a point-in-time snapshot of the routing table of that router. IP Guide parses that file, rebuilds it in memory, and attaches other relevant data to each IP range (also known as a "prefix").
This allows the service to stay fast and stateless, which was one of the main things I was trying to optimize for when building it.
[1]: https://blog.apnic.net/2021/06/04/storing-and-retrieving-ip-... [2]: https://ris.ripe.net/docs/10_routecollectors.html
