Pi-Hole used dnsmasq and modified it. Pi-Hole encourages users to forward DNS queries to (so-called "upstream") third party DNS providers; I think it comes with presets for GoogleDNS and others. I try to avoid dnsmasq (it is often used by default on OpenWRT) as well as third party DNS. I love the idea behind Pi-Hole but I cannot get excited about the implementation.

If I were to make a "Pi-Hole", I would use nsd, tinydns and haproxy. There would be no need for third party DNS. For anyone that wanted to use third party DNS, optionally I would provide dnscache. It's easy to take public DNS blocklists and "import"^1 them into dnscache.

There are lots of other interesting "alternative Pi-Hole" ideas yet to be tried.

1. dnscache uses the filesystem for nameserver manipulation instead of lists. Each domain is a file in the root/servers folder. Each file contains the address of a (blackhole) nameserver.