# GMT Time vs しまった？ 鍵・電気の消し忘れ防止

The clearest difference is in-app purchases: しまった？ 鍵・電気の消し忘れ防止 at none against GMT Time's 1. しまった？ 鍵・電気の消し忘れ防止 also leads on update cadence (every 3 months vs every 28 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. GMT Time sells 1 one-off in-app purchase. しまった？ 鍵・電気の消し忘れ防止 asks for nothing beyond the download.

GMT Time ships an update every 28 months, しまった？ 鍵・電気の消し忘れ防止 every 3 months. The most recent releases landed on November 3, 2026 and November 5, 2026 respectively.

## The numbers

| Metric | GMT Time | しまった？ 鍵・電気の消し忘れ防止 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (38 ratings)](https://appshunter.io/ios/app/gmt-time/id1613023691/reviews)** | — |
| Number of ratings | **38** | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | Yes |
| Update frequency | Every 28 months | **Every 3 months** |
| Monetization | Ad-supported | — |
| Size | 26 MB | 8 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [MingChun Chien](https://appshunter.io/developer/1181368598) | [Takumi Nakamura](https://appshunter.io/developer/1847153717) |

## What reviewers say

### GMT Time

[App page](https://appshunter.io/ios/app/gmt-time/id1613023691)

This app provides accurate GMT time using NTP protocol and TrueTime framework. It offers a timekeeping function, allows setting time between two locations for itineraries, and supports multiple languages. Enjoy precise timekeeping with 1/100 second accuracy.

**Highlights:** Accurate GMT time display, NTP and TrueTime framework integration, Timekeeping function (on/off), Set time between two locations, Multi-language support (English, Japanese, Chinese, Cantonese), 1/100 second accuracy

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Time117 Pro | $0.99 | one-time |


### しまった？ 鍵・電気の消し忘れ防止

[App page](https://appshunter.io/ios/app/id6767480624)

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

**In-app purchases:** none


## Frequently asked questions

### Is GMT Time free?

GMT Time is free to download, with in-app purchases available.

### Is しまった？ 鍵・電気の消し忘れ防止 free?

しまった？ 鍵・電気の消し忘れ防止 is free to download, with no in-app purchases.

### Do GMT Time or しまった？ 鍵・電気の消し忘れ防止 have ads?

Both GMT Time and しまった？ 鍵・電気の消し忘れ防止 show ads.

### Which is updated more often, GMT Time or しまった？ 鍵・電気の消し忘れ防止?

GMT Time ships an update every 28 months, and しまった？ 鍵・電気の消し忘れ防止 every 3 months. Most recently, GMT Time was updated on November 3, 2026 and しまった？ 鍵・電気の消し忘れ防止 on November 5, 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.*