Stay away from SpamZilla they are refusing to provide me a refund because I opened a PayPal dispute, the domains they find are not worth the money you pay monthly, you are better off going to the free expireddomains.net website to find expired/expiring domains as you would find better or even the same domains they have listed. Going on since the end of July and they still refuse to provide me with a full refund, shamefull business pratices.
Domcop - Domcop allows you to find 2million+ expired domains and all of its pat information.
PowerDNS - PowerDNS offers open source DNS software, services, and support.
Expired Domains - Information about Expired Domain Names. Check the Availability of thousands of Expired Domains every day before they Drop and after. Just pick what you like!
dnsmasq - Dnsmasq is a lightweight, easy to configure DNS forwarder and DHCP server.
Domain Scout - Tools to help you discover great domain names for your projects.
Unbound - Unbound is a validating, recursive, and caching DNS resolver.