redirect folder

I have set folder type for my language. Our default language is english and seconrady is german. Now when user goes domain.com user is redirected to domain.com/en/ but we would like to redirect to go german site domain.com/de/

I know i could change default language to german but our default language actually is english but only on frontend we would like to the defaul address to be directed to german. Is there function for this?