42 Attendance Reminder by Primoux

On attendance.42lyon.fr, an attendance session expires after 4 hours. Once that deadline passes, time no longer counts, and nothing alerts you to it — you only discover it by checking your logtime.

42 Attendance Reminder monitors your session and alerts you before the deadline.

Configurable notice period, 30 minutes by default, then regular reminders and priority alert in the last 5 minutes.
Works even without the attendance tab open: an alarm takes over and the counter continues.
One click on the notification opens the attendance page.
The popup displays the remaining time and exact expiration time.
Badging in again postpones the deadline: the alert cycle starts from scratch.

No data leaves your browser: no server, no account, no tracking, no ads. The extension reads your campus attendance page and keeps your settings in local storage.

Written in JavaScript, with zero dependencies.