Steadfastness, one day at a time.
Reminders fire while this app is open (foreground or a background tab), or shortly after you open an installed home-screen icon. Mobile browsers don't allow exact-time alarms when fully closed without a push server, so for prayer times especially, pair this with your phone's azan app for the loudest signal — this is your visual/checklist backup.
Add Istiqamah to your home screen for the full app feel.