Services like Hubspot, Leadlander and even the Google Analytics network domain function reverse lookup the WHOIS information for the visitor’s IP address to sometimes find the company domain of the visitor.
In some cases, the visitor’s organization may be acting as their own Internet Service Provider, and that information is reflected in the WHOIS lookup of the IP address. At other times, the organization may use a third party ISP like Comcast Business, and Comcast Business provides the organization’s name on the WHOIS record.
(Remember: you can always perform a manual whois lookup from an online tool like network-tools.com or via the command line.)
However, in my 20+ years of experience on the Internet, IP WHOIS lookup for an originating organization is maybe 70% accurate if you are very lucky. As of right now, there is no convention compelling ISPs to publish customer information - business or individual - on IP WHOIS records. Back in the day, Pacific Bell used to provide the customer name on the WHOIS for static IPs, but then there were privacy concerns for the customer.
In addition, I’ve heard of some marketing automation tools being able to identify a current visitor from an organization if a previous visitor with that same IP address (or IP address block) had given information to someone else using the marketing automation tool. You should consult your software provider on if/how they implement this “secondary lookup” method.
Post inspired by this Quora thread.