# CrowdMag vs O

The clearest difference is ads: CrowdMag at none against O's shown. O's advantage is update cadence (every 2 weeks vs every 2 months) and iOS requirement (12.0 vs 15.0). On price, in-app purchases and device support there is nothing between them.

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

CrowdMag ships an update every 2 months, O every 2 weeks. The most recent releases landed on October 9, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | CrowdMag | O |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.3 (24 ratings)](https://appshunter.io/ios/app/crowdmag/id910578825/reviews)** | — |
| Number of ratings | **24** | — |
| Positive reviews | 52.9% of reviews | — |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | Every 2 months | **Every 2 weeks** |
| Monetization | Free | — |
| Size | 18 MB | 52 MB |
| Requires iOS | 15.0 | **12.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [University of Colorado Boulder](https://appshunter.io/developer/972210292) | [O-Pitblast, Lda.](https://appshunter.io/developer/1190650181) |

## What reviewers say

### CrowdMag

[App page](https://appshunter.io/ios/app/crowdmag/id910578825)

This app allows users to measure and contribute to scientific research on Earth's magnetic field using their smartphone. It offers features for recording magnetic data during various activities, including flights, and provides tools for data visualization and analysis.

**Highlights:** Measure magnetic field data, Contribute to scientific research, Record data during flights, Visualize data on maps and graphs, Magnetic calculator with WMM2020, Live magnetic compass, Export data via email/Google Drive

**Features:** macOS Compatibility

**In-app purchases:** none


### O

[App page](https://appshunter.io/ios/app/o-pit-blasting-guide/id1645853605)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is CrowdMag free?

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

### Is O free?

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

### Do CrowdMag or O have ads?

O shows ads; CrowdMag does not.

### Which is updated more often, CrowdMag or O?

CrowdMag ships an update every 2 months, and O every 2 weeks. Most recently, CrowdMag was updated on October 9, 2026 and O on October 1, 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.*