# CO2 sensor vs Frequency Analyzer

The clearest difference is rating: Frequency Analyzer at 4.5 against CO2 sensor's 3.4. Frequency Analyzer also leads on update cadence (every 8 days vs every 12 months) and ratings volume (169 vs 7). CO2 sensor's advantage is in-app purchases (none vs 11) and device support (4 vs 1). On price and ads there is nothing between them.

Both are free to download. Frequency Analyzer sells 11 in-app purchases, starting at $2.99 per 7 days. CO2 sensor asks for nothing beyond the download.

Frequency Analyzer holds the better App Store score, 4.5 against 3.4. That said, the two scores are not equally well evidenced: Frequency Analyzer has 169 ratings behind it against 7, so its average is the more settled of the two.

CO2 sensor ships an update every 12 months, Frequency Analyzer every 8 days. The most recent releases landed on October 3, 2026 and October 12, 2026 respectively.

## The numbers

| Metric | CO2 sensor | Frequency Analyzer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.4 (7 ratings)](https://appshunter.io/ios/app/co2-sensor/id1643286074/reviews) | **[4.5 (169 ratings)](https://appshunter.io/ios/app/frequency-analyzer/id6468837339/reviews)** |
| Number of ratings | 7 | **169** |
| Positive reviews | — | 10.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 12 months | **Every 8 days** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 0 MB | 35 MB |
| Requires iOS | **15.6** | 17.2 |
| Devices | **iPhone, iPad, iPod, Mac** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [sighmon](https://appshunter.io/developer/377815161) | [Manfred Kuegel](https://appshunter.io/developer/1520736594) |

## What reviewers say

### CO2 sensor

[App page](https://appshunter.io/ios/app/co2-sensor/id1643286074)

Monitor CO2, temperature, and humidity levels in real-time using a Bluetooth sensor. Save readings with location data and sync them across Apple devices via iCloud. View historical data on a map.

**Highlights:** Real-time CO2, temperature, and humidity readings, Bluetooth sensor integration, Save readings with location, iCloud sync across devices, Map view of saved readings, Open source code available

**Features:** Vision Pro support

**In-app purchases:** none


### Frequency Analyzer

[App page](https://appshunter.io/ios/app/frequency-analyzer/id6468837339)

Transform your device into a professional audio analysis tool with advanced FFT analysis, SPL monitoring, and detailed visualizations. Record, analyze, and export audio data with precision calibration and multiple weighting filters.

**Highlights:** Real-time FFT analysis, Calibrated SPL measurements, 32-bit float audio recording, Synchronized video recording, Spectrogram and octave band analysis, Export WAV, CSV, images, and videos

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

**In-app purchases (11)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Frequency Analyzer Pro Weekly | $2.99 | per 7 days |
| Frequency Analyzer Pro Monthly | $3.99 | per month |
| Frequency Analyzer Pro Monthly | $3.99 | per month |
| Frequency Analyzer Pro Monthly | $4.99 | per month |
| Frequency Analyzer Pro Monthly | $4.99 | per month |
| Frequency Analyzer Pro Monthly | $4.99 | per month |
| Frequency Analyzer Pro Annual | $29.99 | per year |
| Frequency Analyzer Pro Annual | $44.99 | per year |
| Frequency Analyzer Pro Annual | $44.99 | per year |
| Frequency Analyzer Pro Annual | $44.99 | per year |
| Pro access for lifetime | $89.99 | one-time |


## Frequently asked questions

### Is CO2 sensor free?

CO2 sensor is free to download, with no in-app purchases.

### Is Frequency Analyzer free?

Frequency Analyzer is free to download, with in-app purchases available.

### Which has better reviews, CO2 sensor or Frequency Analyzer?

Frequency Analyzer is rated higher. CO2 sensor averages 3.4 out of 5 from 7 ratings, while Frequency Analyzer averages 4.5 from 169 ratings.

### Do CO2 sensor or Frequency Analyzer have ads?

Neither CO2 sensor nor Frequency Analyzer shows ads.

### Which is updated more often, CO2 sensor or Frequency Analyzer?

CO2 sensor ships an update every 12 months, and Frequency Analyzer every 8 days. Most recently, CO2 sensor was updated on October 3, 2026 and Frequency Analyzer on October 12, 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.*