Babbel – the language learning site competing with the likes of Mango Languages, LiveMocha and LingQ among others – has been free for a year now. However, it releases its first premium product tomorrow in the first sign of a business model. Their single payment for a language course differs from the subscription models of other sites, as it’s formed with the idea to make costs more transparent for the customer. But will switching on paid-courses slow their growth? Co-founder Markus Witte tells me “We’re not switching, premium products are an add-on. The site stays free. We’ll loose nobody.”