# SmartAlarm+3 vs BT21

The clearest difference is update cadence: SmartAlarm+3 at every 4 months against BT21's every 10 months. BT21's advantage is iOS requirement (12.4 vs 15.6). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

SmartAlarm+3 ships an update every 4 months, BT21 every 10 months. The most recent releases landed on October 25, 2026 and September 29, 2026 respectively.

## The numbers

| Metric | SmartAlarm+3 | BT21 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 4 months** | Every 10 months |
| Size | 307 MB | 23 MB |
| Requires iOS | 15.6 | **12.4** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Pyronix Ltd.](https://appshunter.io/developer/906273568) | [Thermogroup UK](https://appshunter.io/developer/915777303) |

## What reviewers say

### SmartAlarm+3

[App page](https://appshunter.io/ios/app/smartalarm-plus-3/id1532876579)

**Features:** Apple Wallet

**In-app purchases:** none


### BT21

[App page](https://appshunter.io/ios/app/bt21/id1561931603)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is SmartAlarm+3 free?

SmartAlarm+3 is free to download, with no in-app purchases.

### Is BT21 free?

BT21 is free to download, with no in-app purchases.

### Do SmartAlarm+3 or BT21 have ads?

Neither SmartAlarm+3 nor BT21 shows ads.

### Which is updated more often, SmartAlarm+3 or BT21?

SmartAlarm+3 ships an update every 4 months, and BT21 every 10 months. Most recently, SmartAlarm+3 was updated on October 25, 2026 and BT21 on September 29, 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.*