Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. If you use your computer in only one (human) language, you may not need to be taking up space on your hard drive with extraneous localization files. Monolingual will locate and eliminate these space-wasting files.
Monolingual was written by J. Schrier and I. Stein, and is released under the GNU General Public License. Source code is available.
Note: Now requires OS X 10.10.3 or later.