Language Transfer vs IndoorCO2Map Data Collector
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Language Transfer
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.
- Free audio courses
- Downloadable lessons
- Progress saving
- Offline listening
- No sign-up required
- Multiple languages available
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Language Transfer provides free audio courses that teach you to take control of your thought process. There's no sign-up required — just pick a language and start learning! Available courses: - Complete Spanish - Complete Greek - Complete Swahili - Complete German (work in progress) - Introduction to Arabic - Introduction to Turkish - Introduction to Italian - Introduction to French - Inglés Completo (para Hispanohablantes) - Introduction to Music Theory This app provides the same audio available for free on languagetransfer.org, but allows you to download tracks in advance, save your progress, and listen with your phone locked. We collect some anonymous usage data so we can improve the app and learn about how users are engaging with the lessons. You can learn more in the About section of the app, or turn off this data collection in the Settings pane. The source code for the Language Transfer app is available on GitHub: github.com/language-transfer
IndoorCO2Map Data Collector
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.
- 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
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This App is part of the IndoorCO2map.com project , a citizen data collection initiative to collect data about the CO2 concentration in non-residential Buildings (shops, restaurants, hospital etc.). Using this app and a supported CO2 Sensor, you can help creating a large and comprehensive dataset about Indoor CO2-Levels. Currently Aranet , Airvalent, AirSpot and the Inkbird-IAMT1 Sensors are supported.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | Language Transfer | IndoorCO2Map Data Collector |
|---|---|---|
| Price | Free | Free |
| Rating | 4.9 (1.6K ratings) | 5.0 (3 ratings) — better |
| Positive reviews | 94.1% of reviews | 100.0% of reviews — better |
| Number of ratings | 1.6K — better | 3 |
| Update frequency | Every 14 months | Every 3 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Best chart rank | #178 — better | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 15.1 | 15.0 — better |
| Further details — not scored | ||
| Size | 79 MB | 101 MB |
| Age rating | 4+ | 4+ |
| Developer | Mihalis Eleftheriou | Aurel Wuensch |
Customer experience
Language Transfer
IndoorCO2Map Data Collector
Bugs and requests
Language Transfer
Reported bugs
3 issues- Lessons not always marked as complete correctly
- App sometimes reverts to earlier lessons unexpectedly
- Occasional audio playback issues
Requested features
4 requests- Add more language options
- Improve lesson navigation and progress tracking
- Implement playback speed controls
- Provide transcripts or subtitles for lessons
IndoorCO2Map Data Collector
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Language Transfer
No in-app purchases
IndoorCO2Map Data Collector
No in-app purchases
Questions
Is Language Transfer free?
Is IndoorCO2Map Data Collector free?
Which has better reviews, Language Transfer or IndoorCO2Map Data Collector?
Do Language Transfer or IndoorCO2Map Data Collector have ads?
Which is updated more often, Language Transfer or IndoorCO2Map Data Collector?
Other comparisons
