i18n-tasks finds and manages missing and unused translations in your application. The default approach to locale data management with gems such as i18n is flawed. If you use a key that does not exist, this will only blow up at runtime. Keys left over from removed code accumulate in the resource files and introduce unnecessary overhead on the translators. Translation files can quickly turn to disarray.
i18n-tasks improves this by using static analysis. It scans calls such as
I18n.t('some.key') and provides reports on key usage, missing, and unused keys.
It can also can pre-fill missing keys, including from Google Translate, and it can remove unused keys as well.
i18n-tasks can be used with any project using i18n (default in Rails), or similar, even if it isn't ruby.