YellendarLet your calendar yell at you
A macOS banner shows for about five seconds, in a corner, and then it is gone. Yellendar takes the whole screen and stays until you snooze it, skip it, or join. The rest of the time it is a countdown in the menu bar.
It takes the screen
A banner you can miss by looking away is not an alarm. This covers what you are doing and stays there until you answer it. That is the whole idea, and it is either what you want or it is not.
Loud is a dial
Seven alert styles, from the full takeover above to a quiet strip down one side. Filter by title, organiser or location so it only shouts about the things worth shouting about, and set how many minutes of warning you get, travel time included.
$4.99, once
Not a subscription. Not a trial that quietly lapses. Not a free tier with a nag in it. The nearest thing to it on the Mac charges every year; this asks once and then leaves you alone.
Nothing leaves your Mac
No account, no analytics, no network access. It reads your calendars through macOS and keeps what it finds on the machine. The App Store's own privacy label reads "Data Not Collected", and Little Snitch will tell you the same thing without taking anyone's word for it.
One click into the meeting
Zoom, Meet and Teams open in the app you already have rather than in a browser tab that asks you to open the app.
The fine print, before you ask
macOS 12 and later. It reads your calendars, which macOS will ask you to allow the first time. Version 1.1.10.