# JouleBug vs Zero CO2

The clearest difference is rating: Zero CO2 at 5.0 against JouleBug's 4.4. Zero CO2 also leads on review sentiment (100% vs 70%) and update cadence (every 3 days vs every 3 months). JouleBug's advantage is in-app purchases (none vs 1) and ads (none vs shown). On price and device support there is nothing between them.

Both are free to download. Zero CO2 sells 1 one-off in-app purchase. JouleBug asks for nothing beyond the download.

Zero CO2 holds the better App Store score, 5.0 against 4.4. That said, the two scores are not equally well evidenced: JouleBug has 41 ratings behind it against 4, so its average is the more settled of the two. Written reviews point the same way: 70% of JouleBug's written reviews are positive against 100% of Zero CO2's.

JouleBug ships an update every 3 months, Zero CO2 every 3 days. The most recent releases landed on November 6, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | JouleBug | Zero CO2 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.4 (41 ratings)](https://appshunter.io/ios/app/joulebug-legacy/id391199306/reviews) | **[5.0 (4 ratings)](https://appshunter.io/ios/app/zero-co2-get-climate-neutral/id1534365588/reviews)** |
| Number of ratings | **41** | 4 |
| Positive reviews | 70.0% of reviews | **100.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 3 months | **Every 3 days** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 70 MB | 40 MB |
| Requires iOS | **13.0** | 15.5 |
| Devices | iPhone, iPod | iPhone, iPod |
| Age rating | 12+ | 12+ |
| Developer | [Cleanbit Systems, Inc.](https://appshunter.io/developer/391199309) | [Caramba App Development](https://appshunter.io/developer/349530108) |

## What reviewers say

### JouleBug

[App page](https://appshunter.io/ios/app/joulebug-legacy/id391199306)

This app is designed to enhance workplace experiences by fostering environmental and social stewardship through collective action. It offers tailored sustainability programs, tracks impact metrics, and encourages employee engagement through challenges and social interactions.

**Highlights:** Employee Engagement Hub, Tailored Sustainability Programs, Metrics for Impactful Insights, Inspirational Challenges, Dynamic Social Interactions

**Features:** macOS Compatibility

**In-app purchases:** none

**What reviewers like**

- 💡 Great concept and idea
- 👍 Fun and engaging
- 🌍 Motivates environmental action
- 💡 Educational and informative
- 🤝 Social and competitive aspect

**What reviewers complain about**

- 🐛 App crashes frequently
- 🐛 App is buggy
- 🐛 Server errors
- 🐛 Incomplete features/buttons
- 🐛 Outdated content (challenges, actions)

**Reported bugs**

- App closes when buzzing
- Server error prevents usage
- App won't load after initial setup
- Login errors, requires Facebook
- Accidental buzzes cannot be deleted

**Requested features**

- Add more sustainable actions/challenges
- Update book and movie options
- Add a clothing section with sustainable options
- Allow deletion of unintentional buzzes
- Favorite/categorize activities


### Zero CO2

[App page](https://appshunter.io/ios/app/zero-co2-get-climate-neutral/id1534365588)

This app tracks your phone's carbon footprint from data usage and helps you offset emissions by planting trees. Monitor your CO2 output and see how your reforestation efforts compensate for it, receiving certificates for each planted tree.

**Highlights:** Monitors phone carbon footprint, Tracks CO2 emissions from data usage, Compensates emissions by planting trees, Visualizes CO2 emissions and tree compensation, Provides certificates for planted trees

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Plant your tree | $0.99 | one-time |


## Frequently asked questions

### Is JouleBug free?

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

### Is Zero CO2 free?

Zero CO2 is free to download, with in-app purchases available.

### Which has better reviews, JouleBug or Zero CO2?

Zero CO2 is rated higher. JouleBug averages 4.4 out of 5 from 41 ratings, while Zero CO2 averages 5.0 from 4 ratings.

### Do JouleBug or Zero CO2 have ads?

Zero CO2 shows ads; JouleBug does not.

### Which is updated more often, JouleBug or Zero CO2?

JouleBug ships an update every 3 months, and Zero CO2 every 3 days. Most recently, JouleBug was updated on November 6, 2026 and Zero CO2 on November 3, 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.*