Free

Details

  • Released
  • Updated
  • October 7, 2014
  • March 11, 2026

Features

CrowdMag screenshot #1 for iPhone
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About

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.

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
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What's New in CrowdMag

2.2.7

March 11, 2026

Fixing channel selection in My Data tab

User reviews

I’m dumb but I’m sure it’s useful🤷🏼‍♂️

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.

Terrible app

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

Excellent and extremely useful

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.
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Needs a slight facelift

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.

Was great, but latest update is broken

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

Developer apps

FAQ

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.