That's because the people who pay 20K to 100K USD per application to license it from Sleepycat (now Oracle) typically hide the fact they use it inside their own

That's because the people who pay 20K to 100K USD per application to license it from Sleepycat (now Oracle) typically hide the fact they use it inside their own expensive proprietary stuff. Oracle claims 200 million deployments here - http://www.oracle.com/database/berkeley-db/index.html http://www.oracle.com/database/berkeley-db/index.html Mike Olson says Google, Amazon and Cisco all use it here - http://searchenterpriselinux.techtarget.com/news/article/0,289142,sid39_gci1071880,00.html http://searchenterpriselinux.techtarget.com/news/article/0,2... Amazon SimpleDB is rumored to be Erlang + BerkeleyDB - http://chatterbox.pydinner.org/post/21675996 http://chatterbox.pydinner.org/post/21675996 Sun ran into some trouble a while back when they used it as part of their Java Desktop without the proper license. They ended up paying a few million to avoid a lawsuit and put a positive PR spin on the whole thing here: http://www.redorbit.com/news/technology/16328/sun_microsystems_selects_sleepycat_software_for_new_middleware_and_desktop/ http://www.redorbit.com/news/technology/16328/sun_microsyste... The lesser known (and BSD licensed) db 1.85 library still works well for a lot of applications. db 1.85 has a few bugs in the btree delete and overflow page logic which are easy to deal with. Perforce for example uses their own (fixed) fork of db 1.85 for their depot metadata.