I've searched around a while and all of the IP --> Hostname things actually only end up giving an ISP. Is there something that goes beyond that? I'm only finding pay services that go further and not something that I can just tap a nice API and programmatically do it.
http://ipinfo.io/ just ends up showing ISP for many of what I've sampled. I saw that guy posts here fairly often.
whoisvisiting.com runs about $99/mnth for what my company site does but in that range I'd rather code something. I'm using the free trial right now and have the IP's logging to analytics so I'm looking at what it returns, what IIS returns as the hostname and what a couple sources like ipinfo.io show and whoisvisiting somehow actually shows what I'm looking for.
There's no way to do so. There's no central registry for which company has which address ranges. In fact, most companies will just be identifiable via their ISP.
Your paid services might be scams, by the way, or just work on very few select companies and universities that actually act as autonomous entities in the IP sense.