Our website provides a free download of Serenity 1.0.4 for Mac. The actual developer of this free Mac application is jmitch.com. The program lies within Lifestyle Tools, more precisely General.
From the developer:
Silence OSX notifications sounds, including Skype and Slack, with Serenity . Serenity is a solution designed for the hyper-connected world, removing annoyances such as e-mail, Twitter, and Facebook notifications, and letting you focus on the stuff you actually need to get done.
You may want to check out more Mac applications, such as Serena, My Living Desktop or Osmos, which might be similar to Serenity.