OFFLINE is an Android app developed by Kurt Yu that aims to help users read LINE and Messenger messages without leaving a trace or notifying the sender that the message has been read. The app supports all kinds of messages, including private chat messages, group chat messages, and stickers.

To use the app, users need to open the notification settings for LINE and Messenger and enable notifications and show preview. Additionally, users need to grant OFFLINE notification access in the Android settings. The app requires two permissions: ACCESS_NETWORK_STATE for advertisements and WRITE_EXTERNAL_STORAGE for image cache.

Overall, OFFLINE is a handy tool for those who want to read their messages without notifying the sender. With its support for various message types and ease of use, it is a useful addition to any Android device.