Toki (時), pronounced "toe-key", is the Japanese word for "time". Toki sports a minimal feature set, showing how much of the day you spend on your computer, and how long you spend in each application.
Toki uses App.net as a backend to backup and sync your activity information. Choosing to do so is not required, and the app will continue to function normally. Please note that all synced data is stored in a private stream, visible only to yourself.
If you choose to turn sync on, you will be able to see the aggregate statistics accumulated over all computers logged in to the same computer.