The Stuttgart Open (sponsored since 2022 by Hugo Boss and called the BOSS Open) is an ATP Tour 250 series professional tennis tournament on the ATP Tour. Between 1970 and 1989, the Stuttgart Open was a Grand Prix tennis circuit event. From 1990 to 1999, the Stuttgart Open was an ATP Championship Series tournament. The Championship Series name was changed to ATP International Series Gold in 2000, and the Stuttgart Open was a part of this series from 2000–2001 and 2003–2008. In 2002, the Stuttgart Open was briefly demoted for one year to ATP International Series status, which was renamed to the ATP Tour 250 in 2009, and it has retained the classification ever since.
Held since 1916 in Stuttgart, Germany and prior to the beginning of World War II the tournament was known as the Championships of Stuttgart, following the second world war its was branded as the Stuttgart International Championships or the Stuttgart Weissenhof International. The Stuttgart Open was played on clay up to and including 2014. Starting in 2015, the tournament is played on grass. Along with the move to grass courts, the tournament is now staged in the week after the French Open finishes.Under the sponsorship of Mercedes-Benz, the tournament champions were awarded a Mercedes car, in addition to the prize money.