# CrowdMag

> Measure and contribute to magnetic field research using your smartphone. (iPhone/iPad app by University of Colorado Boulder.)

- Source: https://appshunter.io/ios/app/crowdmag/id910578825 (this page in markdown: same URL + `.md`)
- Developer: [University of Colorado Boulder](https://appshunter.io/developer/972210292)
- Category: Utilities
- Price: Free
- Rating: 4.30/5 from 24 App Store ratings · 16 written reviews indexed
- Age rating: 4+
- Requires: iOS 15.0 · 18 MB
- Languages: American English
- Released: 2014-10-07
- Data updated: 2026-08-15
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/crowdmag/id910578825/reviews.md

## What is CrowdMag?

Introducing CrowdMag's newest feature: Flight Mode, which lets you contribute to scientific research by measuring the magnetic field as you fly around the world. To get started, simply provide your itinerary on the CrowdMag app, and you'll be able to turn your flight into a scientific expedition. Check out this step-by-step tutorial for measuring data while flying: https://geomag.colorado.edu/crowdmag-flight-mode-tutorial .

CrowdMag is an app that lets you measure the local magnetic field using your smartphone. You can view the data as a graph or a map in nanotesla units. CrowdMag measures the Z (downward component), H (horizontal intensity), and F (total intensity) magnetic field components. You can use CrowdMag for measuring magnetic data during outdoor activities, while flying, or to conduct your own experiments. You can also share it with NOAA to help scientists better understand Earth's magnetic field.

If you're going for a walk, run, or other outdoor activities, you can use CrowdMag to measure the magnetic data along your path and save it as a "magtivity." And, if you get a new phone, don't worry! You can export a backup of your CrowdMag data and save it on your computer. This way, if you have to reset your phone or switch to a new one, you can import your backup and continue using CrowdMag without losing your data or progress.

CrowdMag also has a magnetic calculator that provides magvar (declination), the magnetic field's dip angle, total magnetic field, and other magnetic field components based on the latest World Magnetic Model (WMM2020). Some of the other features of CrowdMag include creating your own magtivities, customizing recording frequency and location accuracy, exporting your data via email or Google Drive, and seeing generalized crowdsourced magnetic data from other users.

And, before we forget, CrowdMag also features a compass that distinctly shows both true and magnetic north. As an added feature, the compass also has a 3D display with an optional audio output - check it out!

CrowdMag features: 

* Create your own magnetic activity (called a "magtivity")
* Measure data while flying
* Customize recording frequency and location accuracy to your preferences
* View your magnetic data on an interactive Google Map
* Graph your data as a time series line chart
* Check the quality of your data by comparing it with the World Magnetic Model (WMM)
* Export your data as a CSV file
* Clear stored data on your phone when you want to start fresh
* Choose to share your data with NOAA (optional)
* See generalized crowdsourced magnetic data from other users
* Use the live magnetic compass for 2D and 3D rendering
* View information about the current solar magnetic disturbance
* Use the most up-to-date magnetic field model (WMM2020)
* Export your data via email, Google Drive, or other options
* Export a CrowdMag backup to save your contributions' status and data
* Import your CrowdMag backup (works across different phone platforms)


Visit https://geomag.colorado.edu/crowdmag to see crowdsourced magnetic data .

## Key features

- 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

## Recent user reviews (10 of 16)

All indexed reviews: https://appshunter.io/ios/app/crowdmag/id910578825/reviews.md

### 5/5 — I’m dumb but I’m sure it’s useful🤷🏼‍♂️

*2024-11-24*

I don’t understand it but it seems really cool and useful for researchers and Chat gpt actually recommended it to me. This is now gonna be my compass app.

### 1/5 — Terrible app

*2024-10-10*

This is king Jack and it doas not do what it was supposed it was glitchy and not correct no one should use this app it’s terrible

### 5/5 — Excellent and extremely useful

*2024-08-31*

I often use a mirror compass in conjunction with a spotting scope at peaks or lookouts. I use this combination for looking at features marked on the map or at night in conjunction with astronomy apps which give times and bearings for spotting things such as the space station.
So I find this app a great quick and easy way of getting mag information for wherever it is I happen to be.
Highly recommended.

### 3/5 — Needs a slight facelift

*2023-03-24*

I’m always appreciative of being given opportunities to contribute to wards citizen science, I just wish they’d give the UI on this app an update. It looks best on an iPhone 4 screen. There’s so much more potential with an interface update.

### 1/5 — Was great, but latest update is broken

*2022-11-09*

Per title, latest update broke the app - magnetic declination is zero, i.e. true north = magnetic north

### 3/5 — Seems cool....but setting options need work

*2019-08-31*

I am unable to enable background recording because my location data isn’t set to “Always” but I don’t have an “Always” option for the app in setting. Only Never and While Using App.

### 1/5 — No location

*2019-03-09*

iPhone XS Max —- doesn’t grab GPS location. I emailed back and forth with support. Known bug. Fix for 5 stars.

### 1/5 — 1.7.5 cannot take location from at least some iPhones

*2019-02-19*

iPhone 5s 32GB iOS 12.1.4 App never acquires location data from the phone and therefore never records data. I reported this to NOAA just last week. It would be interesting to hear from people using newer, more capable iPhones, although no mention is made of any limitations on older phones. 

Makes a very nice compass app though.

### 1/5 — CrowdMag is useless.

*2019-02-09*

It has a bug with my iPhone7+, iOS 12.1.4
Its not grabbing my gps data from phone. 
It has no info/help tab. 
Why use a Mag model at all?? If we are going to provide mag heading, dip and uT, app could compute/derive nPole location from all our inputs. App could then plot it in quazi real time, send alerts etc. 
An almost good app but...

### 5/5 — Zero effort to contribute to cool research

*2018-05-27*

Just open the app and set how often you want to send them data. These types of apps are a great way to harness the power of your iPhone and with no effort make a positive contribution. Nice touch adding achievements for contributions and locations. The magnetic information is interesting to see but that’s about it. Just know your contribution will help other researchers.

## Frequently asked questions about CrowdMag

### What is CrowdMag used for?

CrowdMag allows you to measure the local magnetic field using your smartphone. You can view this data as a graph or map and contribute to scientific research by sharing it with NOAA.

### Can I measure magnetic data while flying with CrowdMag?

Yes, CrowdMag's Flight Mode lets you contribute to scientific research by measuring the magnetic field as you fly. Simply provide your itinerary in the app to turn your flight into a scientific expedition.

### How accurate is the magnetic data from CrowdMag?

CrowdMag allows you to check the quality of your data by comparing it with the World Magnetic Model (WMM2020), which is the most up-to-date magnetic field model.

### Can I save my CrowdMag data if I get a new phone?

Yes, you can export a backup of your CrowdMag data and save it on your computer. This allows you to import your backup and continue using CrowdMag without losing your data or progress on a new phone.

### Does CrowdMag have ads?

CrowdMag is free and does not contain advertisements, allowing for an uninterrupted user experience.

### What magnetic field components does CrowdMag measure?

CrowdMag measures the Z (downward component), H (horizontal intensity), and F (total intensity) magnetic field components, as well as providing magvar (declination) and dip angle.

### What devices does CrowdMag support?

CrowdMag is available on iPhone, iPad, and iPod devices, making it accessible to a wide range of Apple users.

### How often is CrowdMag updated?

The latest version of CrowdMag is 2.2.7, and it was last updated on March 11, 2026, indicating ongoing development and support.

## Version history (last 5 releases)

### 2.3.0 — 2026-08-14

* Fully migrating to University of Boulder Colorado servers

### 2.2.7 — 2026-03-11

Fixing channel selection in My Data tab

### 2.2.6 — 2026-02-19

* Updating send feedback email to crowdmag@colorado.edu

### 2.2.5 — 2026-01-26

* Making app work for liquid glass design
* 1 Sec polling rate recording will now automatically keep the screen on 
* Made the default calculator model WMMHR

### 2.2.4 — 2026-01-23

* Making app work for liquid glass design
* 1 Sec polling rate recording will now automatically keep the screen on 
* Made the default calculator model WMMHR

## Apps similar to CrowdMag

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [VuSitu](https://appshunter.io/ios/app/vusitu/id1448937574) | 4.9 (16) | Free | Utilities |
| [StraboField](https://appshunter.io/ios/app/strabofield/id1555903455) | 4.5 (19) | Free | Utilities |
| [Polar Scope Align Pro](https://appshunter.io/ios/app/polar-scope-align-pro/id970161373) | 4.9 (300) | $3.99 | Utilities |
| [Magnetic Storms](https://appshunter.io/ios/app/magnetic-storms/id575956246) | 4.3 (19) | Free | Utilities |
| [Geode Connect](https://appshunter.io/ios/app/geode-connect/id1446098695) | 3.8 (9) | Free | Utilities |
| [LinkComm](https://appshunter.io/ios/app/linkcomm/id590256859) | 4.7 (3) | Free | Utilities |

## More apps by University of Colorado Boulder

- [COTWINS](https://appshunter.io/ios/app/cotwins/id983798285)
- [CU Boulder Wise Law Library](https://appshunter.io/ios/app/cu-boulder-wise-law-library/id984606007)
- [The Herd CU](https://appshunter.io/ios/app/the-herd-cu/id1008541707)
- [Science at 100,000 Feet](https://appshunter.io/ios/app/science-at-100000-feet/id1065022210)
- [CU Boulder Life](https://appshunter.io/ios/app/cu-boulder-life/id1089430197)

All apps by University of Colorado Boulder: https://appshunter.io/developer/972210292

## Related topics

[magnetscape](https://appshunter.io/ios/topics/magnetscape) · [the source crowd](https://appshunter.io/ios/topics/the-source-crowd) · [crowdsorsa](https://appshunter.io/ios/topics/crowdsorsa) · [magnetic interference](https://appshunter.io/ios/topics/magnetic-interference)

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-15.*