# Ultrasonic Repeller vs EMF Detector

The clearest difference is price: EMF Detector at Free against Ultrasonic Repeller's $0.59. EMF Detector also leads on rating (4.3 vs 3.6) and update cadence (every 2 weeks vs every 2 months). Ultrasonic Repeller's advantage is in-app purchases (none vs 3) and review sentiment (44% vs 25%). On ads and device support there is nothing between them.

EMF Detector is free to download; Ultrasonic Repeller costs $0.59 up front. EMF Detector sells 2 in-app purchases, starting at $4.99 per month. Ultrasonic Repeller asks for nothing beyond the download.

EMF Detector holds the better App Store score, 4.3 against 3.6. That said, the two scores are not equally well evidenced: EMF Detector has 319 ratings behind it against 51, so its average is the more settled of the two. Written reviews complicate that: 44% of Ultrasonic Repeller's written reviews are positive against 25% of EMF Detector's, so the app with the better star average is not the one people write more warmly about.

Ultrasonic Repeller ships an update every 2 months, EMF Detector every 2 weeks. Both last shipped on October 18, 2026.

## The numbers

| Metric | Ultrasonic Repeller | EMF Detector |
| --- | --- | --- |
| Price | $0.59 | **Free** |
| Rating | [3.6 (51 ratings)](https://appshunter.io/ios/app/ultrasonic-repeller/id445318668/reviews) | **[4.3 (319 ratings)](https://appshunter.io/ios/app/emf-detector-radiation-reader/id6572300713/reviews)** |
| Number of ratings | 51 | **319** |
| Positive reviews | **43.6% of reviews** | 25.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 2 weeks** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 2 MB | 11 MB |
| Requires iOS | 16.1 | **13.0** |
| Devices | iPhone, Apple Watch | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Aleksandr Balyberdin](https://appshunter.io/developer/336185043) | [新雨 李](https://appshunter.io/developer/1559932632) |

## What reviewers say

### Ultrasonic Repeller

[App page](https://appshunter.io/ios/app/ultrasonic-repeller/id445318668)

This app uses ultrasound technology to create a protective barrier against insects, rodents, and aggressive dogs. It also offers features for personal space and experimental bat deterrence, with advanced controls and Apple Watch integration.

**Highlights:** Insect repellent, Rodent deterrent, Dog deterrent, Personal space protector, Apple Watch support, High-precision frequency generator, Background mode

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none

**What reviewers like**

- ✅ Effective on mosquitoes and insects
- ✅ Works on rodents when volume is high
- ✅ Free app with no cost
- ✅ Simple and intuitive interface
- ✅ Multiple pest settings available

**What reviewers complain about**

- ❌ Inconsistent effectiveness across different pests
- ❌ Doesn't work on dogs or older animals
- ❌ Requires high volume to be effective
- ❌ Limited range of effectiveness
- ❌ Effectiveness diminishes over time as pests adapt

**Reported bugs**

- App crashes on startup (multiple iOS versions)
- Incompatible with iOS 8 and older versions
- App force closes when screen is locked
- Crashes on iPhone 6s and later models
- No sound output on iPad 1

**Requested features**

- Add cat repeller mode
- Add bat repeller mode
- Add ant repeller mode
- Add fly repeller mode
- Add snake repeller mode


### EMF Detector

[App page](https://appshunter.io/ios/app/emf-detector-radiation-reader/id6572300713)

Transform your iPhone into an EMF detector to monitor electromagnetic fields. Identify radiation levels in various environments to assess safety at home, work, or in public spaces. Gain insights to make informed decisions about your surroundings.

**Highlights:** EMF monitoring, Electromagnetic field detection, Radiation level measurement, Environmental safety assessment, Real-time EMF readings

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| unlimited features | $4.99 | per month |
| unlimited features | $14.99 | one-time |


## Frequently asked questions

### Is Ultrasonic Repeller free?

Ultrasonic Repeller costs $0.59, with no in-app purchases.

### Is EMF Detector free?

EMF Detector is free to download, with in-app purchases available.

### Which has better reviews, Ultrasonic Repeller or EMF Detector?

EMF Detector is rated higher. Ultrasonic Repeller averages 3.6 out of 5 from 51 ratings, while EMF Detector averages 4.3 from 319 ratings.

### Do Ultrasonic Repeller or EMF Detector have ads?

Neither Ultrasonic Repeller nor EMF Detector shows ads.

### Which is updated more often, Ultrasonic Repeller or EMF Detector?

Ultrasonic Repeller ships an update every 2 months, and EMF Detector every 2 weeks. Most recently, Ultrasonic Repeller was updated on October 18, 2026 and EMF Detector on October 18, 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.*