A webcam can't sense airflow, so this watches whether your lips are parted — all on your device. The green/red outline traces your lips and the line shows the gap it measures. When your mouth stays open past your threshold for the hold time, it assumes mouth breathing and alerts with sound plus a red flash. Talking briefly won't trigger it — that's what the hold time is for. Use Calibrate to fit the threshold to your face.

Runs in the background. It keeps watching (and alerting) even when this tab is hidden or another app is focused. It only stops if the whole computer sleeps.