Whisper is one of a growing group of social networks designed to let its users post anonymous messages for the world to read. But where Secrets takeup in Silicon Valley means the app plays host to rumors about tech companies and their products, Whisper is home to a different kind of confession. In tone, Whisper feels closest to PostSecret. Founded in 2005, PostSecret played host to a range of user-submitted confessions that ranged from the mundane to the serious, and were all set against carefully designed, postcard-sized images.