The church registers of the Austrian dioceses (except those of the Diocese of Eisenstadt) have all been digitised and can be accessed online. For conservational reasons, it is no longer possible to work with the originals whenever online church registers are available.
www.matricula-online.eu (Archdioceses of Vienna and Salzburg; Dioceses of St. Pölten, Linz, Gurk-Klagenfurt, Feldkirch, Graz-Seckau)
https://apps.tirol.gv.at/bildarchiv (Diocese of Innsbruck)
https://matriken.graz-seckau.at (Diocese of Graz-Seckau)