Satvis vs Flow Alert
Price, ratings, monetisation and update history for both apps, side by side ā with what reviewers say about each.
Satvis
Visualize and track thousands of satellites in real-time on a 3D globe. See upcoming passes over your location and identify satellites in the sky view. This free, open-source app provides detailed spacecraft information and works offline.
- Real-time 3D satellite visualization
- Upcoming pass predictions
- Ground-level sky view
- Detailed spacecraft information
- Offline functionality
- Customizable map views
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Satvis is a free, open-source satellite tracker for iPhone and iPad. It draws more than 16,000 satellites on a 3D globe in real time: Starlink, GPS, weather satellites, the ISS and many more. Set your location and it predicts when each one passes overhead. The sky view shows the sky from where you stand. Point your phone up to see the satellites in that direction. WHAT IT DOES ⢠Visualize satellites on a 3D globe in real time, propagated on the device with SGP4 from CelesTrak's element sets ⢠Show points, labels, orbits, orbit tracks, ground tracks, sensor cones, 3D models and ground station links per satellite, colored by orbit class (LEO, MEO, GEO, HEO) ⢠Switch catalog groups on and off (Starlink, GNSS, weather, Earth observation, crewed stations), or search for a single satellite ⢠Select a satellite to see its orbit, its next passes over your locations and its spacecraft details: country, operator, manufacturer, bus, mass and size ⢠Track a satellite: the camera flies to it and follows it along its orbit ⢠Save your location or any point you pick on the map, then list the upcoming passes over it and get a notification before one starts ⢠Find satellites overhead in the ground-level sky view, aimed by dragging or by pointing your phone, with the camera's picture of the sky behind them ⢠See which satellites you could spot: the sky view dims those in Earth's shadow, too far away or in a daylit sky ⢠View the globe in 3D or flattened to 2D, over the base map, star field and terrain you choose: satellite imagery, Earth at night or the day's VIIRS imagery ⢠Start from the featured views, bookmark your own, and share any view as a link: it opens the same view on satvis.space ⢠Open satvis.space links straight in the app ⢠Keep using it offline, from the satellite data it last fetched WHERE THE DATA COMES FROM Element sets come from CelesTrak, refreshed several times a day, and are propagated on your device with SGP4. Spacecraft details come from Jonathan McDowell's GCAT. FREE AND OPEN SOURCE No account, no ads, no in-app purchases. Developed in the open at github.com/Flowm/satvis under the MIT license.
Flow Alert
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Flow Alert provides quick access to flow , stage, temperature, and turbidity data made available by the United States Geologic Survey (USGS). Download USGS gauges and add favorites to a separate list. Create nicknames for your favorite gauges. Add a widget on your home screen that shows your selected parameter for your favorite gauges. Currently, widgets update automatically approximately every 15 minutes and show a bell icon if an alert is triggered. Add alerts to notify yourself when your gauge meets your defined criteria. Multiple alerts may be set for each favorite gauge. Manage your alerts for all gauges in one screen. Select a gauge from the list to see an interactive graph of the past 7 days of available data. Data provided by: -United State Geological Survey (USGS) Disclaimer: Flow Alert provides quick access to flow , stage, temperature, and turbidity data made available by the United States Geologic Survey (USGS) via USGS Water Data APIs. All data shown in Flow Alert are downloaded from the USGS Water Data APIs. Flow Alert is not affiliated with, endorsed by, or representative of any government entity including USGS. Flow Alert does not take credit, responsibility, or ownership for any data downloaded from USGS's Water Data API. It is simply a tool that you can use to view the data made available by USGS. Data Source Link: https://api.waterdata.usgs.gov/ If you have feedback, suggestions, or feature requests, please e-mail me at flowalertapp@gmail.com...I'd appreciate it! You may also submit feedback through the in-app feedback page.
Screenshots
Verdict
The clearest difference is update cadence: Satvis at every 3 weeks against Flow Alert's every 7 months. Flow Alert's advantage is iOS requirement (15.0 vs 26.0). On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price Ā· Rating Ā· Positive reviews Ā· Number of ratings Ā· Update frequency Ā· Ads Ā· In-app purchases Ā· Monetization Ā· Best chart rank Ā· Devices Ā· Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Satvis ships an update every 3 weeks, Flow Alert every 7 months. The most recent releases landed on November 6, 2026 and October 31, 2026 respectively.
| Parameter | Satvis | Flow Alert |
|---|---|---|
| Price | Free | Free |
| Positive reviews | 0.0% of reviews | ā |
| Update frequency | Every 3 weeks ā better | Every 7 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | ā |
| Devices | iPhone, iPad | iPhone, iPad, iPod ā better |
| Requires iOS | 26.0 | 15.0 ā better |
| Further details ā not scored | ||
| Size | 12 MB | 34 MB |
| Age rating | 4+ | 4+ |
| Developer | Florian Mauracher | Shaina Schwartzel |
In-app purchases
Satvis
No in-app purchases
Flow Alert
No in-app purchases









