# CalendarDuo vs ShiftPay Calendar

The clearest difference is in-app purchases: CalendarDuo at none against ShiftPay Calendar's 3. ShiftPay Calendar's advantage is ads (none vs shown) and update cadence (every 5 days vs every 4 months). On price, device support and iOS requirement there is nothing between them.

Both are free to download. ShiftPay Calendar sells 3 in-app purchases, starting at $1.99 per month. CalendarDuo asks for nothing beyond the download.

CalendarDuo ships an update every 4 months, ShiftPay Calendar every 5 days. The most recent releases landed on October 15, 2026 and October 4, 2026 respectively.

## The numbers

| Metric | CalendarDuo | ShiftPay Calendar |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 4 months | **Every 5 days** |
| Monetization | Ad-supported | — |
| Size | 41 MB | 1 MB |
| Requires iOS | 15.1 | **15** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Chun Lam](https://appshunter.io/developer/1565498900) | [定云 张](https://appshunter.io/developer/6776453615) |

## What reviewers say

### CalendarDuo

[App page](https://appshunter.io/ios/app/calendarduo/id1589593639)

Easily manage and view holidays from two different countries simultaneously. This utility app offers instant switching between calendars, a dual-view display, and helpful tools like a world clock and currency exchange.

**Highlights:** Switch between two world calendars instantly, Duo-view with holidays from two countries, Daylight Saving Time dates, Currency exchange rate, World clock, Add notes

**Features:** macOS Compatibility

**In-app purchases:** none


### ShiftPay Calendar

[App page](https://appshunter.io/ios/app/shiftpay-calendar/id6776539730)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| ShiftPay Pro Monthly | $1.99 | per month |
| ShiftPay Pro Annual | $14.99 | per year |
| ShiftPay Pro Lifetime | $24.99 | one-time |


## Frequently asked questions

### Is CalendarDuo free?

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

### Is ShiftPay Calendar free?

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

### Do CalendarDuo or ShiftPay Calendar have ads?

CalendarDuo shows ads; ShiftPay Calendar does not.

### Which is updated more often, CalendarDuo or ShiftPay Calendar?

CalendarDuo ships an update every 4 months, and ShiftPay Calendar every 5 days. Most recently, CalendarDuo was updated on October 15, 2026 and ShiftPay Calendar on October 4, 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.*