Use APKPure App
Get Egg Timer old version APK for Android
A very simple countdown timer. Its raison d'être is ease of use - only one click to start the timer.
Long-press the buttons to edit the times. Options->Setting for vibrate, volume etc.
Useful for many activities: meditation, exercise, etc.
Update: Should fix sleep-related bugs.
Donations welcome (press menu in app)! :-)