Monotone is no longer in general use. As of late 2023, these are the only projects known to be using it, and neither has updated in over a decade.

Project	First commit	Last update
monotone	2003-09-04	2011-10-11
MegaLettering	2003-02-20	2009-01-18

No longer using monotone

Project	switched to	switched when
Pidgin (formerly Gaim)	mercurial	early 2012
Dropbear SSH	mercurial	ca. Sept 2011
I2P	git	unknown
Botan	git	unknown
PacketFence	git	unknown