Looking for a "Registered domain research tool"

[DomainEmpire.com]

I'm looking for a website/script/tool to query current Zone Files by keyword, to see all registered domains containing the specified word.

In the past I used domainsurfer.com which closed a couple of years ago then I used whois.net which's no longer working since few months while recently I was using namedroppers.com which's currently offline.

Is there any alternative free/paid solution to conduct such queries ?
Thanks for helping.

 

[Michael]

This one is pretty good:

http://domain-search.domaintools.com/

I don't think it includes every single domain, but it is pretty darn exhaustive and you have the option to include deleted and expired domains in the search.

 

[DomainEmpire.com]

Thanks for helping Michael, other members suggested the same tool and yes, I admit it's an excellent solution to my problem