Comparison

World Time Shifter Clock vs Must Ring

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

World Time Shifter Clock

This app helps you manage time across different time zones for global coordination. Easily plan meetings, stay connected with loved ones, and track events worldwide. Its intuitive display and time-shifting feature make it simple to understand and use.

Highlights
  • Intuitive world clock display
  • Time shifting for time zone comparison
  • Meeting scheduling across time zones
  • Travel time forecasting
  • Event reminders and notifications
Features
Read full description

Coordinate with anyone, any time, anywhere, around the world with this unique and intuitive world clock. SYNC TEAMS - schedule overlap feature makes it easy to see when everyone's schedule coincides. KEEP IN TOUCH - Stay connected to family around the globe - know when it's the best time to call your relatives in another time zone. GREAT FOR TRAVEL - Plan your travel - use it to forecast your landing time after a long flight thru multiple time zones. GLOBAL SPORTS MATCHES - Don't miss the opening kick-off of the match in Manchester. TRADING MARKETS - Stay on top of the financial markets around the world. Features • Unique Intuitive Display - Super easy to see the times around the world • Time Shifting: Rotate the clock forwards or backwards to see time changes. • Large Widget - see the full clock face right on your home screen. • Schedule Overlap - see hours of overlap for schedules in one or more locations. • Reminders: Creates notifications for any time, any place.

About

Must Ring

Features
Read full description

Must Ring is for the handful of things that cannot be missed — medication, picking someone up, the one task that has to happen today. Not a to-do list. Not a habit tracker. Just the few alarms that have to land, and an honest record of whether they did. RINGS THROUGH SILENT AND FOCUS Built on Apple's AlarmKit, so it rings full-screen like the system alarm — Silent on, any Focus mode, after the app is closed, after a restart. Two buttons on the Lock Screen: Done, or Snooze. IF NOBODY ANSWERS, SOMEONE GETS TOLD Set a delay. If the alarm still isn't confirmed after it, Must Ring sends a message to the contact you chose — so a missed dose doesn't pass in silence. You decide what they see. EVERY RING LEAVES A TRACE Done, done after snooze, skipped, unconfirmed, never delivered — each one is written down with its time and where you answered it (Lock Screen, widget or in the app). You can always tell "I forgot" apart from "it never rang". TEN TEMPLATES, THREE FIELDS Medication, meeting, pickup, errand, birthday, anniversary and more. Pick one, set the time, set the repeat. Lead time from 5 minutes up to a week. IN CHINA: STATUTORY WORKDAYS A work alarm can follow the official holiday calendar — it rings on make-up workdays and stays quiet on public holidays. A WIDGET THAT ANSWERS THE QUESTION What's next, how long is left, how today is going — on the Home Screen, without opening anything. PRIVATE BY DEFAULT Everything stays on your iPhone. No account, no sign-in, no server, no profiling. FREE TO START Same-day alarms always work, and so does the basic record — free, no account. A one-time purchase unlocks unlimited alarms, the template pack, escalation to a contact and full export. No subscription. Must Ring does not provide medical advice and is not a medical device. Always follow your prescriber's instructions.

Screenshots

World Time Shifter Clock4 screens
Must Ring4 screens

Verdict

The call

The clearest difference is in-app purchases: World Time Shifter Clock at none against Must Ring's 1. World Time Shifter Clock also leads on iOS requirement (18.0 vs 26.1). Must Ring's advantage is ads (none vs shown). On price, update cadence and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Must Ring sells 1 one-off in-app purchase. World Time Shifter Clock asks for nothing beyond the download.

UpkeepUpdate frequency

World Time Shifter Clock ships an update every 3 weeks, Must Ring fortnightly. The most recent releases landed on November 3, 2026 and October 31, 2026 respectively.

Scorecard3 real differences · 7 level
World Time Shifter Clock versus Must Ring: the parameters behind the verdict, then further details
ParameterWorld Time Shifter ClockMust Ring
PriceFreeFree
Rating4.4 (98 ratings) — better—
Positive reviews100.0% of reviews—
Number of ratings98 — better—
Update frequencyEvery 3 weeksFortnightly — better
AdsYesNo — better
In-app purchasesNo — betterYes
MonetizationAd-supported—
DevicesiPhone, iPad — betteriPhone
Requires iOS18.0 — better26.1
Further details — not scored
Size23 MB12 MB
Age rating4+4+
DeveloperDavid Richmond大胜 纪

In-app purchases

None

World Time Shifter Clock

No in-app purchases

1 purchases

Must Ring

One-time1
  • Must Ring Unlock$14.99

Questions

Is World Time Shifter Clock free?
World Time Shifter Clock is free to download, with no in-app purchases.
Is Must Ring free?
Must Ring is free to download, with in-app purchases available.
Do World Time Shifter Clock or Must Ring have ads?
World Time Shifter Clock shows ads; Must Ring does not.
Which is updated more often, World Time Shifter Clock or Must Ring?
World Time Shifter Clock ships an update every 3 weeks, and Must Ring fortnightly. Most recently, World Time Shifter Clock was updated on November 3, 2026 and Must Ring on October 31, 2026.

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