In Croatia, Rupp families are Croats (from Zagreb ).
Prevalence
About 10 people with faimily name Rupp live in Croatia today, in one household only. They are located in one Croatian city only, in Zagreb (<5).
Outside Croatia
Family name Rupp is present in 64 countries worldwide. The family name "Rupp " is used by some 20000 people in Germany , about 20000 in the United States , and some 2000 people in Brazil.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over five times, the first time 1917 in source List of Dignitaries, Officials and Public Servants of the Kingdom of Croatia-Slavonia.