# Language Transfer vs IndoorCO2Map Data Collector

The clearest difference is ratings volume: Language Transfer at 1.6K against IndoorCO2Map Data Collector's 3. Language Transfer also leads on chart position (#178 vs unranked). IndoorCO2Map Data Collector's advantage is update cadence (every 3 months vs every 14 months). On price, rating, review sentiment and ads there is nothing between them.

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

On the App Store both sit at effectively the same score — 4.9 for Language Transfer against 5.0 for IndoorCO2Map Data Collector. That said, the two scores are not equally well evidenced: Language Transfer has 1.6K ratings behind it against 3, so its average is the more settled of the two. Written reviews are what separate them: 94% of Language Transfer's written reviews are positive against 100% of IndoorCO2Map Data Collector's.

Language Transfer ships an update every 14 months, IndoorCO2Map Data Collector every 3 months. The most recent releases landed on November 7, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Language Transfer | IndoorCO2Map Data Collector |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (1.6K ratings)](https://appshunter.io/ios/app/language-transfer/id1519599004/reviews) | **[5.0 (3 ratings)](https://appshunter.io/ios/app/indoorco2map-data-collector/id6504560820/reviews)** |
| Number of ratings | **1.6K** | 3 |
| Positive reviews | 94.1% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 14 months | **Every 3 months** |
| Monetization | Free | Free |
| Best chart rank | **#178** | — |
| Size | 79 MB | 101 MB |
| Requires iOS | 15.1 | **15.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Mihalis Eleftheriou](https://appshunter.io/developer/1519599306) | [Aurel Wuensch](https://appshunter.io/developer/1752859912) |

## What reviewers say

### Language Transfer

[App page](https://appshunter.io/ios/app/language-transfer/id1519599004)

**Currently charting:** #178 Top Free · Education (US App Store)

Learn new languages and music theory through free, downloadable audio courses. This app offers a structured approach to language learning, allowing you to track progress and listen offline. No sign-up is necessary to begin your educational journey.

**Highlights:** Free audio courses, Downloadable lessons, Progress saving, Offline listening, No sign-up required, Multiple languages available

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

**In-app purchases:** none

**What reviewers like**

- 🚀 Highly effective language learning method
- 👍 Intuitive and logical approach
- 🤩 Incredible value for being free
- 💡 Unique teaching style that builds on existing knowledge
- 🎉 Accelerates language learning progress

**What reviewers complain about**

- 🐛 App has some bugs and stability issues
- 🔍 Lack of playback controls (speed, rewind, etc.)
- 🗂️ Difficulty navigating and finding specific lessons

**Reported bugs**

- Lessons not always marked as complete correctly
- App sometimes reverts to earlier lessons unexpectedly
- Occasional audio playback issues

**Requested features**

- Add more language options
- Improve lesson navigation and progress tracking
- Implement playback speed controls
- Provide transcripts or subtitles for lessons


### IndoorCO2Map Data Collector

[App page](https://appshunter.io/ios/app/indoorco2map-data-collector/id6504560820)

Contribute to a citizen science project by collecting indoor CO2 concentration data in public buildings. Use a supported CO2 sensor and this application to build a comprehensive dataset for analysis.

**Highlights:** Collect indoor CO2 concentration data, Supports Aranet, Airvalent, AirSpot, Inkbird-IAMT1 sensors, Contribute to citizen science project, Builds comprehensive indoor CO2 dataset, Data collection for non-residential buildings

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Language Transfer free?

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

### Is IndoorCO2Map Data Collector free?

IndoorCO2Map Data Collector is free to download, with no in-app purchases.

### Which has better reviews, Language Transfer or IndoorCO2Map Data Collector?

IndoorCO2Map Data Collector is rated higher. Language Transfer averages 4.9 out of 5 from 1.6K ratings, while IndoorCO2Map Data Collector averages 5.0 from 3 ratings.

### Do Language Transfer or IndoorCO2Map Data Collector have ads?

Neither Language Transfer nor IndoorCO2Map Data Collector shows ads.

### Which is updated more often, Language Transfer or IndoorCO2Map Data Collector?

Language Transfer ships an update every 14 months, and IndoorCO2Map Data Collector every 3 months. Most recently, Language Transfer was updated on November 7, 2026 and IndoorCO2Map Data Collector on October 30, 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.*