Portal Timer is an Android application that tracks and times the cool down periods of Ingress portal hack. This app is a simple tool that sits in your notification tray, making it easy to access and use. The app is free to download and use, and it is open source, licensed under GPLv3. You can get the source code on GitHub.

The app is straightforward to use. Once you have installed it, Portal Timer will run silently in the background. You will receive a notification when the cool down period is over. The app is very lightweight and does not consume much battery or memory. Overall, Portal Timer is a handy tool for Ingress players who want to keep track of their portal hack cool down periods.