To avoid such problems in Rack/Rails Ruby project I suggest the rack-i18n_best_langs gem (regardless of the name, it does not depend on the i18n gem) I wrote:

To avoid such problems in Rack/Rails Ruby project I suggest the rack-i18n_best_langs gem (regardless of the name, it does not depend on the i18n gem) I wrote: https://github.com/gioele/rack-i18n_best_langs > Differently from other similar Rack middleware components, rack-i18n_best_langs returns a list of languages in order of guessed importance, not a single language. > Language discovery is done using three clues: > * the presences of language tags in paths (e.g. /service/warranty/ita), > * the content of the HTTP Accept-Language header, > * the content of the rack.i18n_best_langs cookie when set.