# World Timezone Calendar vs Opti

The clearest difference is in-app purchases: Opti at none against World Timezone Calendar's 1. Opti also leads on ads (none vs shown) and update cadence (monthly vs every 4 months). On price and device support there is nothing between them.

Both are free to download. World Timezone Calendar sells 1 one-off in-app purchase. Opti asks for nothing beyond the download.

World Timezone Calendar ships an update every 4 months, Opti monthly. The most recent releases landed on September 26, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | World Timezone Calendar | Opti |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.9 (295 ratings)](https://appshunter.io/ios/app/world-timezone-calendar/id792552743/reviews)** | — |
| Number of ratings | **295** | — |
| Positive reviews | 76.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 4 months | **Monthly** |
| Monetization | Free with in-app purchases | — |
| Size | 19 MB | 30 MB |
| Requires iOS | 16.6 | **11.0** |
| Devices | **iPhone, iPad, Mac, Apple Watch** | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Geospike Pty Ltd](https://appshunter.io/developer/500622151) | [Hydrite Chemicals](https://appshunter.io/developer/1702029715) |

## What reviewers say

### World Timezone Calendar

[App page](https://appshunter.io/ios/app/world-timezone-calendar/id792552743)

Easily schedule meetings and events across different time zones. This app helps you find the perfect time for global coordination by comparing multiple time zones and integrating with your existing calendar. Plan ahead with future time views and share events that automatically adjust to recipients' local times.

**Highlights:** Cross-timezone scheduling, View calendar in multiple timezones, Time travel to plan ahead, Add unlimited timezones, Day/night indicators, Home screen widget, Global event sharing

**Features:** Apple Watch app

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Advertising | $19.95 | one-time |

**What reviewers like**

- 👍 Easy to use
- 🌍 Great for multiple time zones
- 💡 Simple and efficient
- ✅ Clear display
- 🤝 Helpful for international scheduling

**What reviewers complain about**

- 💰 Expensive ad-free version
- 🔞 Inappropriate ads in free version
- 💸 High price for functionality

**Reported bugs**

- 🐛 Inappropriate ads in free version
- 🐛 Widget settings not saved
- 🐛 Cannot add new events with double tap
- 🐛 Timezone abbreviations not displayed
- 🐛 Search feature doesn't work

**Requested features**

- Add more cities
- Option to freeze time zones for comparison
- Switch between 24-hour and AM/PM clock
- Cleaner design with better calendar event integration
- Ability to pick a specific date to view


### Opti

[App page](https://appshunter.io/ios/app/opti-lock/id6670614547)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is World Timezone Calendar free?

World Timezone Calendar is free to download, with in-app purchases available.

### Is Opti free?

Opti is free to download, with no in-app purchases.

### Do World Timezone Calendar or Opti have ads?

World Timezone Calendar shows ads; Opti does not.

### Which is updated more often, World Timezone Calendar or Opti?

World Timezone Calendar ships an update every 4 months, and Opti monthly. Most recently, World Timezone Calendar was updated on September 26, 2026 and Opti on September 17, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*