Stand Reminder is a free, open-source macOS menu bar app that actually makes you stand up. Unlike apps that send system notifications you can swipe away, Stand Reminder shows a modal above all other apps — dismissible only by clicking "I stood up!" This small friction is the whole point. Set reminders by interval or at specific times of day. The modal resets after sleep, appears on whichever display your cursor is on, and supports dark mode. No account. No tracking. Just stand up.