Apache Nutch
Common Crawl – publicly available internet-wide crawls, started using Nutch in 2014.
Creative Commons Search – an implementation of Nutch, used in the period of 2004–2006.
DiscoverEd – Open educational resources search prototype developed by Creative Commons
Krugle uses Nutch to crawl web pages for code, archives and technically interesting content.
mozDex (inactive)
Wikia Search - launched 2008, closed down 2009
https://en.wikipedia.org/wiki/Apache_Nutch