The official language in Austria is German.

An excerpt from the article 31 facts about Austria

It is Austrian German, the national variety of German, which is the native language of 88.6% of the population. Six national minorities recognized by Austria live mainly in the south of the country: Croats, Slovaks, Slovenians, Czechs, Hungarians, and Roma. Therefore, there are regional official minority languages there: Croatian (Burgenland-Croatian, spoken by approximately 19.5 thousand inhabitants of Burgenland), Slovenian and Hungarian.