Collateral is an Android productivity application that allows users to create notes and lists in their notification area, so they can have reminders for important tasks or to-do lists available from anywhere. The app offers access to all 500+ notification icons, and the created notifications can be saved for reuse and edited completely. Users can also change default notification icons, colors, and options, as well as enable night mode based on time or indefinitely. Additionally, notifications can be shared to and created from other apps, and there are notification and widget shortcuts to create notes and lists.

Collateral also offers pro features, such as the ability to sign in with Google to manually sync notifications, add actions to notes to perform tasks from the notification, add pictures to notes to display them within the notification, and add reminders to notifications to create them at a certain time. Users can also export notifications to backup or import on another device, share pictures from other apps to create notes with them, and receive reminder notifications to show upcoming reminders.

Overall, Collateral is a useful and efficient productivity app for Android users who want to keep their notes and lists organized and easily accessible.