Say you are on a website example.com and would like to know which other web domains are owned by the same person who owns that example.com website. Is it possible?

Yes there are some easy workarounds (and tools) that can help you find domains owned by an individual or a company though you may not be successful on every hunt. Let’s give it a try!

Step 1: Reverse Whois Lookups with Google

When you register a web domain, your name, contact address, phone number and other details are stored with the domain in a public registry database that anyone can access online using a Whois Lookup tool.

Go to whois.sc and enter the domain name that you are trying to research. This will provide you contact details of the domain registrant and you can then use this data to perform a reverse whois lookup on Google to find other domains of that person.

“PHONE_NUMBER” site:whois.domaintools.com “STREET_ADDRESS” site:whois.domaintools.com

Replace Phone Number or Street Address in the above search queries with the actual data from the whois database. You may also perform reverse Whois Lookups by name but that may return too many results – phone numbers and postal addresses are more likely to be unique.

Step 2: Perform Reverse IP Lookups

Some domain owners may have opted for “private” registration (Google Apps does this for free) and in that case, their contact details won’t be available in the public whois database.

The next option you should try is a Reverse IP lookup. These tools determine the IP address of the server that is hosting a website - example.com in our example - and will then provide you are list of other websites that are hosted on that same server. The logic is that if a person has multiple websites, he could be using the same web server to host them.

You can use Bing to perform a Reverse IP check for any domain or an even easier tool is spyonweb.com – just put the site’s domain and it will show other websites hosted on that server. If you get hundreds of domains in the search results, it possibly means that the person is using a shared host and thus he may not be the owner of all these domains.

Step 3: Reverse Google AdSense Lookups

If a web domain is using Google AdSense ads, you can use Blekko search to find all the other sites on the web that use the same AdSense ID.

View the HTML page source of any website and look for the AdSense string which has a pattern like ca-pub-1234. The numeric part (1234) is the AdSense ID which you can put into Blekko in the following format:

/adsense=1234

Some of the returned sites could belong to scrapers but you should be able to unearth some legitimate sites as well, if they are also using AdSense.

Step 4. Reverse Google Analytics Lookups

Google AdSense is only popular among content publishers but almost every website is using Google Analytics for traffic statistics. And there are online tools available that can quickly find all websites that are are connected to the same Google Analytics account.

Go to ewhois.com and type the domain name that are you are researching. Next choose the Reverse Google Analytics ID Lookup tab and it should bring a list of all web domains that are connected to the same Google Analytics ID.

This is the most effective option of them all though it would only work for live websites that use Analytics while standard Whois lookups can even find web domains that have only been registered but are not live yet.

Also see: How to Find Person Behind an Email Address