# CO2 Modeller vs KORG GEC5 Controller

The clearest difference is review sentiment: CO2 Modeller at 75% against KORG GEC5 Controller's 25%. CO2 Modeller also leads on device support (3 vs 1). KORG GEC5 Controller's advantage is rating (5.0 vs 2.5) and update cadence (every 11 months vs every 36 months). On price, ratings volume, ads and in-app purchases there is nothing between them.

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

KORG GEC5 Controller holds the better App Store score, 5.0 against 2.5. Both are backed by a comparable volume of ratings — 2 and 4 respectively. Written reviews complicate that: 75% of CO2 Modeller's written reviews are positive against 25% of KORG GEC5 Controller's, so the app with the better star average is not the one people write more warmly about.

CO2 Modeller ships an update every 36 months, KORG GEC5 Controller every 11 months. The most recent releases landed on October 19, 2026 and October 22, 2026 respectively.

## The numbers

| Metric | CO2 Modeller | KORG GEC5 Controller |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [2.5 (2 ratings)](https://appshunter.io/ios/app/co2-modeller/id1037101261/reviews) | **[5.0 (4 ratings)](https://appshunter.io/ios/app/korg-gec5-controller/id1073023302/reviews)** |
| Number of ratings | 2 | **4** |
| Positive reviews | **75.0% of reviews** | 25.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 36 months | **Every 11 months** |
| Monetization | Free | Free |
| Size | 9 MB | 22 MB |
| Requires iOS | 12.1 | **11.0** |
| Devices | **iPhone, iPad, iPod** | iPad |
| Age rating | 4+ | 4+ |
| Developer | [Alex Rogers](https://appshunter.io/developer/346832869) | [KORG INC.](https://appshunter.io/developer/363714046) |

## What reviewers say

### CO2 Modeller

[App page](https://appshunter.io/ios/app/co2-modeller/id1037101261)

Simulate the impact of reducing carbon emissions on climate change. This app generates projections for atmospheric CO2 concentration, global warming, sea level rise, and ocean acidification.

**Highlights:** Model carbon emission reductions, Simulate climate change effects, Project CO2 concentration, Estimate global warming, Predict sea level rise, Analyze ocean acidification

**Features:** macOS Compatibility

**In-app purchases:** none


### KORG GEC5 Controller

[App page](https://appshunter.io/ios/app/korg-gec5-controller/id1073023302)

This software provides a comprehensive system for group instruction in music, language, or technology labs. It offers flexible modes for lectures, individual practice with teacher eavesdropping, and collaborative group work, enhancing classroom efficiency and engagement.

**Highlights:** Multiple practice and instruction modes, Fully-digital stereo sound, Intuitive software user interface, Flexible audio routing, Open curriculum compatibility, Lecture, Practice, and Group modes

**In-app purchases:** none


## Frequently asked questions

### Is CO2 Modeller free?

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

### Is KORG GEC5 Controller free?

KORG GEC5 Controller is free to download, with no in-app purchases.

### Which has better reviews, CO2 Modeller or KORG GEC5 Controller?

KORG GEC5 Controller is rated higher. CO2 Modeller averages 2.5 out of 5 from 2 ratings, while KORG GEC5 Controller averages 5.0 from 4 ratings.

### Do CO2 Modeller or KORG GEC5 Controller have ads?

Neither CO2 Modeller nor KORG GEC5 Controller shows ads.

### Which is updated more often, CO2 Modeller or KORG GEC5 Controller?

CO2 Modeller ships an update every 36 months, and KORG GEC5 Controller every 11 months. Most recently, CO2 Modeller was updated on October 19, 2026 and KORG GEC5 Controller on October 22, 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.*