Hello HN,over the last few weeks for an internal project we (CKIN) have been building Korbinsky, an API allowing to retrieve which hostnames corresponds to a given IP.
Coming from a different background (security and embedded software) this has been an interesting journey tackling various techs and we see no reason not to open (a moderate) usage to developers.
We have created a key for HN so you can start to experiment without registration (which is of course free and available [0]):curl -v -H "apikey: l86WRM0NC2bBHMfEBQdkhXbDp2BoQw0O"  course it works also with other IP addresses :) even the good old IPv4:curl -v -H "apikey: l86WRM0NC2bBHMfEBQdkhXbDp2BoQw0O"  is a quota associated to the key so if you intend to build something it would be better to register your own (or ping us in case of different quota needs).thank you in advance for your precious feedback.Best regards,
CKIN[0] 