What's the difference between time-sensitive notifications and AlarmKit?
Time-sensitive notifications are a priority level inside Apple's existing push notification system; AlarmKit is a separate framework that creates real alarms, not notifications at all. At WWDC 2025 Apple introduced AlarmKit, a framework that lets developers schedule one-time alarms, weekly repeating alarms, and countdown timers, and unlike notifications scheduled with UserNotifications, which stay quiet in silent mode or during a Focus unless the app holds the rarely granted Critical Alerts entitlement, AlarmKit alerts cut through silent mode and focus with a permanent banner and sound.
That last part is the entire story. Time-sensitive notifications were Apple's compromise for apps that needed to interrupt Focus without the full weight of a critical alert. AlarmKit is the opposite approach: instead of nudging the priority of a notification up, it gives the app the same system privileges as the Clock app. The distinction matters for anyone building a reminder app, and it matters just as much for the person deciding why their calendar notifications aren't working the way they expect.
Do time-sensitive notifications work in Focus mode?
Yes, but only partially, and only if the user has allowed it. Even if you have a Focus mode like Do Not Disturb active, Time Sensitive notifications will bypass it to wake up the Lock Screen and play a sound — unless silent mode is activated. That caveat is the part most people miss: Focus and silent mode are two separate gates, and time-sensitive notifications only get through the first one.
Time Sensitive notifications alert you like active ones but also break through Focus mode and Notification Summary settings, so you always see them. They also get special lock screen treatment — they break through your different Focus modes and remain on your Lock Screen for an hour, so you can act on them with urgency. None of that helps if the phone is physically muted, which is the exact scenario that causes most missed meetings. For a deeper walkthrough of how Focus filters notifications before they ever reach your lock screen, see does Focus block calendar alerts.
How do critical alerts compare to AlarmKit alarms?
Critical alerts and AlarmKit both bypass silent mode, but they're built for completely different reasons and one of them you'll almost never get access to. A Critical Alert plays a sound and shows on screen even when the iPhone is muted or in a Focus mode, and because it deliberately overrides the user's silence settings, Apple restricts it to a narrow set of genuinely life-, safety- or health-critical apps.
That restriction is the whole reason AlarmKit exists for everyone else. An Alarm is a permanent alert for pre-determined timely alerts that breaks through silent mode and focus, so users have to consent to a permission dialog — no special entitlement application to Apple required, just a runtime permission prompt like Camera or Location access. Apple is explicit that the two systems aren't interchangeable, though: alarms are great for countdowns with a specific interval or recurring alerts with a schedule, but they are not a replacement for other prominent notifications, like critical alerts or time-sensitive notifications. AlarmKit alarms are for things the user scheduled themselves — a wake-up time, a timer, a meeting start — not for arbitrary third-party messages arriving at unpredictable moments. We cover this distinction in more detail in critical alerts vs AlarmKit on iOS.
| Type | Breaks through Focus | Breaks through silent mode | Needs Apple entitlement |
|---|---|---|---|
| Active notification | No (unless allowed) | No | No |
| Time-sensitive notification | Yes | No | No |
| Critical alert | Yes | Yes | Yes, rarely granted |
| AlarmKit alarm | Yes | Yes | No, user permission only |
Why can't apps just use AlarmKit for everything?
Because AlarmKit was designed for a narrow use case — alarms and countdowns the user explicitly set — not for the broad category of app messaging that notifications handle. A banking app's fraud alert, a messaging app's incoming text, a delivery update: none of those fit the AlarmKit model of a scheduled alarm with a stop button and a snooze button. AlarmKit bypasses Silent mode and Focus modes with the same priority as Apple Clock, and the user controls the privilege via a system permission prompt the first time the app schedules an alarm. That permission prompt is deliberately visible and specific, which is why developers can't quietly reclassify every push notification as an alarm to dodge Focus restrictions.
There's also an adoption gap worth knowing about. Major task managers like Things, Todoist, TickTick, and Microsoft To Do are still using Time Sensitive notifications, not alarms, because migrating means UX changes their existing users may not want. Calendar and reminder apps that do adopt AlarmKit get a meaningfully different experience, which is the entire premise behind what AlarmKit actually is and why it matters for anyone who has ever slept through a meeting because their phone was on silent.
Which one should calendar apps use?
For anything the user needs to physically act on at a specific time — a meeting, a flight boarding call, a medication dose — AlarmKit is the better fit, because time-sensitive notifications still go silent on a muted phone. That gap is precisely why calendar notifications have historically failed people: the event fires a time-sensitive push, Focus lets it through, but the phone is face-down and silenced in a meeting, so nothing is heard. AlarmKit vs notifications on iOS covers the mechanics of why alarms ring louder in more depth.
Pealo is built around this exact gap — it turns Google Calendar, Outlook, and iCloud events into AlarmKit alarms rather than relying on push notifications, so events ring through silent mode and Focus the same way a native iPhone alarm does. If you're comparing options, the rundown of calendar alarm apps for 2026 breaks down which apps use real alarms versus notification tricks, and the calendar alarm app for iPhone page covers setup specifics.
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