Mozart’s full baptismal name was Joannes Chrysostomus Wolfgangus Theophilus Mozart. Joannes Chrysostomus was in reference to Saint John of Chrysostom, whose saint day is the date of Mozart’s birth – January 27 – and Theophilus was in honour of the boy’s godfather, Joannes Theophilus Pergmayr, who was a town councillor in Salzburg. But Mozart’s father often referred to the boy as Gottlieb (a German translation of Theophilus) in honour of this man. “Wolfgang” came from his maternal grandfather.
However, as a child, Mozart’s many names were hardly used and he was known by the nicknames “Wolfgangerl or “Woferl”, which historians can prove by looking at the family’s correspondence. And when he was older, he dropped his first two names.
According to The Treasures of Mozart, he referred to himself as Wolfgango Amadeo, or more often, Wolfgang Amade, but not Amadeus. On some occasions, he went by Wolfgang Gottlieb, Mozart, or even the short forms WMZT or MZT.
Source: The Treasures of Mozart
Photo from Google Images