I use gettext for whatever back-end language I'm using. I much prefer handling this sort of thing from the back-end. That way it doesn't matter what the front-end is. It just works.
For frameworks with gettext we integrate with it! Gettext will extract the phrases into a .po file but these need to be translated. Running 'langapi push' will push out all the .po files in the codebase and running 'langapi pull' will pull the translated versions back in and automatically save them in the correct locations.