Lightning LLC launches MustDo task alarm app for iPhone
Tokyo-based Lightning LLC released MustDo on the Apple App Store, an iPhone app that rings an iOS 26 AlarmKit alarm at a set task time.
Lightning LLC, an app developer based in Tokyo, has launched its schedule management app MustDo for Apple iPhone on the Apple App Store, according to digitaltoday.co.kr. The release adds a second app to the developer's lineup, after KeyAlarm, which turns calendar schedules into alarms.
MustDo rings an iOS 26 AlarmKit alarm at the specified time once a task and time are registered. The alarm appears full-screen even in silent and Focus modes and continues until the user stops it. Stopping the alarm marks the task as complete. Users can also pick "in 10 minutes", "in 1 hour" or "tomorrow" to be reminded again, and if only a task is entered, the default is tomorrow at 9 AM.
Repetition can be set at the level of the iOS calendar, and the app offers 25 types of alarm sounds. Tasks are stored only in the user's Apple iCloud without a server, and no account registration is required. It also supports Model Context Protocol (MCP), so users can ask Claude AI to add a task.
MustDo runs on iPhone with iOS 26 or later and supports 8 languages, including Korean. It offers a 30-day free trial followed by a monthly or annual subscription, with no automatic billing after the trial. Without a subscription, already registered tasks still ring and can be stopped, re-alerted or deleted; a subscription is needed only to register new tasks.
Quick answers
What does the MustDo app do?
It is a schedule management app that rings an iOS 26 AlarmKit alarm at the time set for a registered task, and marks the task complete when the user stops the alarm.
Which devices and languages does MustDo support?
It is available on iPhone with iOS 26 or later and supports 8 languages, including Korean.
Does MustDo require a subscription?
It offers a 30-day free trial followed by a monthly or annual subscription, with no automatic billing after the trial. Without a subscription, registered tasks still ring and can be stopped, re-alerted or deleted, but a subscription is required to register new tasks.