Macs don't have a built-in way to mute or silence the system start up chime. If you’re in a library or coffee shop you don’t always want that start up chime to play. Now you can silence the Mac OS X(Mountain Lion and Mavericks) start up chime with StartNinja. It is a free and simple desktop utility that silences the start up chime and will resume previous sound level after logging in.

Some scenarios in which StartNinja might not work for you.

• Note 1: Does not work with some/many iMacs
• Note 2: The system start up chime is played through the internal speaker. If speakers or headphones are plugged in the system start up chime will still play.