Constance Weber was born on January 5, 1762 in Wiesental / Germany. Father was Franz Fridolin Weber, mother Maria Caecilia and sister Aloysia Weber (married Lange), relative of Carl Maria von Weber (composer). She was educated to Sopran singer.
She became acquainted with Wolfgang Amadeus Mozart 1777 in Mannheim. But Mozart fell in love with her sister.
1781 Mozart met family Weber again, they moved to Vienna meanwhile. Sister Aloysia already was married. For a while Mozart lived in Weber's house as subtenant, but had to move "because of the gossip of the people". 1782 Wolfgang Amadeus Mozart married Constance.
After his death 1791 she organized the publishing of Mozart's works by publisher J.A.André Offenbach. 1809 she married the Danish diplomat Georg Nikolaus Nissen in Bratislava. He is author of Mozart's first biography. Nissens moved to Salzburg 1821. 1826 her man died. She died on March 6, 1842 in Salzburg. Her grave is in St.Sebastians cemetery.