CrowdMag vs Local Sidereal Time
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
CrowdMag
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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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 .
Local Sidereal Time
This app calculates local sidereal time, a system astronomers use to locate celestial objects. It can also be used for personal development, with studies suggesting increased psychic abilities during specific sidereal times. The pro version offers advanced features like notifications and map-based calculations.
- Calculate local sidereal time
- Astronomy celestial object location
- Potential psychic ability enhancement
- Pro version notifications
- Pro version map-based calculation
- Pro version date/time conversion
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Sidereal helps you track local sidereal time from your current location or any place you want to check. It is designed for people interested in the 13:30 LST window discussed in remote-viewing literature, while also supporting any custom sidereal target you want to follow. Use Sidereal to: View a live local sidereal clock based on your current location Calculate local sidereal time manually from longitude, date, and time Search for a city or address and see the result with map support Generate the next 31 upcoming hits for your selected sidereal target Schedule the next 30 days of on-device alerts Export future times to CSV and export events to your calendar Customize your target LST, alert timing, full-window notifications, night viewing, and map visibility Sidereal starts with 13:30 LST as the default target, but you can change it in Settings to track any local sidereal time. The app includes a trial, with Pro unlocking continued access to advanced tools and planning features.
Screenshots
Verdict
The clearest difference is in-app purchases: CrowdMag at none against Local Sidereal Time's 1. CrowdMag also leads on update cadence (every 2 months vs every 4 months). Local Sidereal Time's advantage is rating (4.7 vs 4.3) and ratings volume (1.1K vs 25). On price, ads, device support and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Local Sidereal Time sells 1 one-off in-app purchase. CrowdMag asks for nothing beyond the download.
Local Sidereal Time holds the better App Store score, 4.7 against 4.3. That said, the two scores are not equally well evidenced: Local Sidereal Time has 1.1K ratings behind it against 25, so its average is the more settled of the two. Written reviews point the same way: 53% of CrowdMag's written reviews are positive against 71% of Local Sidereal Time's.
CrowdMag ships an update every 2 months, Local Sidereal Time every 4 months. Both last shipped on October 24, 2026.
| Parameter | CrowdMag | Local Sidereal Time |
|---|---|---|
| Price | Free | Free |
| Rating | 4.3 (25 ratings) | 4.7 (1.1K ratings) — better |
| Positive reviews | 52.9% of reviews | 70.7% of reviews — better |
| Number of ratings | 25 | 1.1K — better |
| Update frequency | Every 2 months — better | Every 4 months |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free — better | Free with in-app purchases |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 15.0 |
| Further details — not scored | ||
| Size | 18 MB | 20 MB |
| Age rating | 4+ | 4+ |
| Developer | University of Colorado Boulder | Scott Spiller |
Customer experience
CrowdMag
Local Sidereal Time
Bugs and requests
CrowdMag
Not enough reviews yet to summarise bugs or requests.
Local Sidereal Time
Reported bugs
4 issues- Alarm doesn't work
- Crashes when loading
- Notification issues
- Pro purchase restoration not working
Requested features
4 requests- Add alarm feature
- Allow setting location manually
- Improve notification handling
- Automatically adjust for daylight saving time
In-app purchases
CrowdMag
No in-app purchases
Local Sidereal Time
- Pro$4.99
Questions
Is CrowdMag free?
Is Local Sidereal Time free?
Which has better reviews, CrowdMag or Local Sidereal Time?
Do CrowdMag or Local Sidereal Time have ads?
Which is updated more often, CrowdMag or Local Sidereal Time?
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