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