TimerLync 사용 가이드

TimerLync is a countdown timer that shows the same time on several devices and sounds the alarm on all of them at the same moment. It runs on iPhone, iPad and Apple Watch, and it does not ask you to create an account or sign in. This guide explains what problem the app is meant to solve, how a first-time user can get started, and how to deal with the places where people most often get stuck.

What problem does it solve?

When several people each set a countdown on their own phone and say "three, two, one, go", the timers drift apart more often than you would expect. Who pressed first, whose screen went to sleep and which phone has a different alarm sound all add up to a few seconds of difference. For classroom group work, meeting time-boxes or team workouts, where everyone should finish at the same instant, that small gap is a constant annoyance.

Instead of sending remaining seconds back and forth, TimerLync shares a single value: the moment the timer ends. Each device corrects its own clock against network time and then counts down to that end time by itself. Devices only need to resynchronize when something changes, such as a pause or added time, so a brief connection wobble does not make the numbers jump around.

Who is it for?

• Teachers and trainers who want every student to see the same clock during group work or presentations.
• Teams that want the presenter and the facilitator to share one sense of time in a meeting.
• Study groups and remote teams who want to try a group pomodoro, where everyone focuses and rests together.
• Coaches, families and housemates who need to line up workout sets or cooking steps.
• Anyone who simply wants a dependable alarm for a solo countdown. A quick timer that needs no room is included.

Screens at a glance

The six images below are store screenshots with a promo headline on top; the screens are the iPhone app. They show how the host and participant screens differ, the start moment and the sequence editor, in that order.

Getting started

1. Install and requirements

Download the app from the App Store. It is built for iOS 17 or later. Finding nearby devices uses the Local Network permission. If you decline it, you can still join a room by typing the room code, which connects through an internet relay.

2. Create a room

1. On the home screen, choose Create Room and pick a countdown duration.
2. Start the session. The room opens and shows a join code and a QR code.
3. Tell the others the code, send it in a chat message, or let them scan the QR code.

3. Join a room

On the joining device, tap Join Room. Rooms opened nearby appear in a list. Pick one, or type the code, and the same countdown screen opens. Participants can join at any time without paying or signing up.

4. Start and control

By default the host controls start, pause and adding a minute. The host can name co-hosts, hand the host role to someone else, or open control to everyone. When two or more devices are in the room, starting shows a 3-2-1 lead-in on every screen, timed against the same shared moment, before the countdown begins. A ready check can hold the start until every participant confirms.

Features worth knowing

Sequences and group pomodoro

A sequence chains several steps into one timer. For example, a ten-minute talk followed by five minutes of Q&A switches on every device at the moment the step changes. The same idea powers a group pomodoro, so a whole team can follow one rhythm of focus and break.

Overtime

If a session runs long, overtime keeps counting past 00:00. The default can differ by version; per the latest development notes it is off by default and you turn it on in settings.

Apple Watch, Lock Screen and widgets

The Apple Watch companion has its own end-of-timer alert, so you can be notified on your wrist even when the phone is elsewhere. The app also offers a live status on the Lock Screen and Dynamic Island, a Lock Screen widget and Siri shortcuts. Some behavior, such as the Watch alert, can only be confirmed on real hardware, so test with your own devices before an important event.

Session history

Finished sessions are kept in a history. Exporting that history as a CSV file is part of the paid Pro unlock.

Free versus Pro

The app offers a one-time Pro unlock, not a subscription. Counted on the host's device, a room holds two devices by default, and Pro raises that to eight. Larger rooms and CSV export are what Pro covers. Joining rooms, the quick timer, sequences and the Watch app have no such limits, and participants never need to buy anything. Check the store page for the current price.

A five-minute pre-event checklist

With a synced timer, one device with notifications off means one device that stays silent. A quick pass in this order just before the event prevents most mishaps.

1. The host creates the room and shows the code and QR. Putting the QR on a big screen makes joining fast.
2. On the participants sheet, check that every device reads "connected". Devices beyond capacity cannot enter, so count how many you need in advance (two by default, eight once Pro is unlocked).
3. Turn on the ready check. It stops the start from happening while someone is not looking at the screen.
4. Run one short test countdown. Confirm the alarm sounds at the same moment on every device and is not blocked by silent or Focus mode.
5. Keep devices that must ring plugged in or charged. The alert is scheduled even if the screen turns off, but a dead battery will not ring.

For a class, the biggest time saver is installing the app and granting permissions on student devices beforehand. Some classroom Wi-Fi blocks device-to-device traffic, so if the test shows no nearby room, tell people to type the code instead.

Practical tips

• Before an event, check notification and Local Network permissions on both the host and the participant devices.
• Do Not Disturb and Focus modes can silence alerts, so set exceptions if needed.
• On networks that isolate devices, such as some classroom Wi-Fi, nearby discovery may fail. Entering the code connects through the internet relay instead.
• If a session might run over, turn overtime on from the start.
• For a fixed agenda like a presentation, one sequence is less error-prone than several separate timers.

Usage by group size, and where it stops fitting

The two-device default and the eight-device Pro capacity are counted from the host device that created the room. Knowing which scenes fit and which do not makes the adoption decision easy.

• 2 devices (default): a presenter and a facilitator, or a coach and an athlete, sharing one clock. You can start without paying.
• 3 to 8 devices (host has Pro): a small study group, one device per group in a lab, a team pomodoro. Participants never pay; only the host unlocks Pro.
• 9 or more devices: a room tops out at eight, so it does not suit a class of 30 each joining on their own phone. Join one representative device per group, or put the host screen on a projector instead.

Troubleshooting

• A nearby room does not show up: confirm both devices are on the same network and the Local Network permission is allowed. If it still fails, type the code.
• A third device cannot join: if the host has not unlocked Pro, the room holds two devices. The host's setting decides, not the joining device's.
• Numbers look off on one or two devices: make sure the date and time are set automatically. The app corrects with network time, but accuracy can suffer where the internet is unreachable.
• The alarm does not sound: check notification permission, silent mode and Focus mode in that order.

Privacy

There are no accounts, no sign-in and no ads. To tell participants apart, a device identifier is kept on the relay server only while the room exists and is deleted when the room goes away. The app does not collect location or contacts. See the privacy policy for details.

Limits and known issues

• It is for iPhone, iPad and Apple Watch only. It needs iOS 17 or later, and there is no Android or Windows app, so Android users cannot join a room.
• Time correction depends on network time. A device that has never reached the internet may be less accurate, and "tens of milliseconds" is a target, not a guarantee.
• OS settings win over the app. The app schedules the end alert ahead of time, but it will not ring if notification permission is off or Focus mode blocks it.
• Some areas need real-device checks, such as the Watch alert and handing the host role to someone else. The development notes also classify them as things a simulator cannot verify, so test with your own devices before an important event.
• Room capacity follows the host. If the host does not have Pro, the limit is two devices, and a joining device paying does not raise it. Buying mid-session cannot be assumed to raise the capacity of remote connections right away (an open item in the development notes), so unlock Pro before creating the room.
• Participant identifiers live on the relay server only while the room exists. They are deleted when the room goes away. Finished sessions stay in the on-device history, and exporting them as CSV is a Pro feature.

How it compares

If everyone can look at one screen, a single big display is easiest. A room makes sense when each person needs to read the time on a personal device (a presenter's monitor, hands-on work while moving around) or when a sound or vibration should land at the same instant. The synchronization idea is explained further in our article on synchronized timers for groups.

Sources and further reading

1. IETF RFC 5905: Network Time Protocol Version 4
2. Apple Developer: Multipeer Connectivity
3. Apple Developer: TN3179 Understanding local network privacy

FAQ