Satellite Trackers Compared: Which One Should You Use?

Free satellite trackers do different jobs, so the right one depends on what you want to see. This guide covers nine of them, ours included. It says what each does best, who it suits, and what WatchSat doesn’t do yet. Everything here is as of October 2026.

By the WatchSat team · Reviewed October 13, 2026 · Sources: each site’s own pages, NASA

Which satellite tracker should you use?

Start from the job you want done.

See the ISS with your own eyes. NASA’s Spot the Station alerts you before a good pass. Heavens-Above and n2yo list passes for a location you give them, and so do WatchSat’s ISS pass predictions.
Catch a Starlink train. FindStarlink does only that. azmth, Orbital Radar, satellitemap.space and WatchSat’s Starlink train page cover trains too.
Get a message before a pass. n2yo sends email and SMS, and Spot the Station has alerts and an app. WatchSat’s email alerts are built but not switched on.
Browse the whole catalog, debris included. satellitemap.space, KeepTrack, n2yo and Orbital Radar each track tens of thousands of objects.
Follow re-entries and close approaches. Orbital Radar and satellitemap.space list them, and KeepTrack has debris tools.
Work out what that light was. azmth and Orbital Radar each have a page for it.
See satellites in a realistic 3D sky. That’s what WatchSat is for: every active satellite, with the Moon, Sun and planets in their real positions, on the live globe.

We make WatchSat, so we aren’t neutral. Every claim about another site below is what that site, its app-store listing or an independent write-up says about it, and each is linked in the sources at the end. We haven’t tested every feature ourselves, and sites change. If something here is out of date, tell us.

What does each satellite tracker do best?

n2yo

n2yo is the long-running lookup tool. Search by name or NORAD ID and a satellite’s page lists its international designator, launch date and period. Its pages show a running count of tracked objects, 34,401 on a page dated June 19, 2026, with debris and rocket bodies included. After you register it can email or text you before a pass, and developers get a keyed API and embeddable widgets. Space.com once introduced a satellite tracker from n2yo. It suits anyone who wants to look up one object, set an alert or build on an API.

Heavens-Above

Heavens-Above is the observer’s tool. Give it a location and it lists passes with the satellite, when it appears, how high it climbs and when it sets. Click a pass and you get a sky chart of the path with times marked, and a daily list shows the brighter satellites up that night. Its explainer page says predictions assume the Sun is at least 6° below the horizon, and it cautions that brightness figures are rough. An Android app works out passes on the phone, so it needs a data connection only every few days. It suits people planning a night of visual observing.

satellitemap.space

satellitemap.space is a WebGL globe covering more than 30,000 satellites, with Starlink shown by default and a view by Starlink generation. A Load menu filters by purpose or project, and by country or the institution that launched them. A satellite’s page shows its hardware and generation, launch date and target altitude. Its info page lists email alerts for Starlink trains that may be visible and a close-approach finder, and there is an iOS app. Pick it if you want to filter the whole catalog and watch Starlink in detail.

KeepTrack

KeepTrack is free, open source and runs in the browser. It’s the most analytical tool here. Its features page cites details on more than 64,000 satellites and debris objects (its operations page says 37,000). It can simulate a breakup and watch the fragments spread, or screen debris near a chosen satellite. You can search by orbital elements and look angles, see a list of next launches, and load other CelesTrak groups through a URL. Its docs say it’s used in operations centers, classrooms and outreach. It’s for students and analysts who want to experiment.

Orbital Radar

Orbital Radar covers a lot of ground. Its globe shows active satellites, the ISS, Starlink trains and tracked debris, and it lists passes over your location. A re-entry tracker uses Tracking and Impact Prediction messages from the US Space Force and shows predicted windows. Skylens is browser AR that labels satellites over your camera feed. Its press page lists close-encounter alerts and re-entry predictions, and says there is no paywall and no app download. It suits people who want re-entries, debris and AR in one browser tab.

azmth.space

azmth.space is similar in shape to WatchSat: a 3D globe of the active satellites, a page for each satellite and constellation, and positions worked out in your browser. Its Product Hunt listing mentions pass predictions for your location, automatic detection of newly launched Starlink trains and a shareable link for each satellite. Its What was that? page takes a time and a place, checks 15,000+ satellites and replays the matches on the globe. It publishes data under CC BY 4.0, and its own comparison page lists no alerts, AR, app or public API. Pick it to work out what a light in the sky was.

FindStarlink

FindStarlink does one thing. Enter a city or coordinates and it lists when Starlink satellites pass over, with a brightness tag, a magnitude and a good, average or poor rating. It follows the first few days after a launch, while the satellites still fly in a line. The iPhone app adds a Remind me alert 30 minutes before a pass and works offline. Local TV stations have cited it. It’s for anyone who wants to catch the next train.

NASA’s Spot the Station

Spot the Station covers the ISS and nothing else. NASA’s Johnson Space Center calculates the sightings for thousands of locations. At its 2012 launch, a sign-up sent an email or text a few hours before a visible pass, only for passes high enough to clear trees and buildings, with morning, evening or both to choose from. NASA officials said the best opportunities come up anywhere from once or twice a week to once or twice a month. The free app for iOS and Android (2023) adds an AR view, 2D and 3D location views and a list of upcoming sightings. Check NASA’s site for the options on offer today. It suits anyone who only wants to know when to step outside for the station.

WatchSat

WatchSat is a 3D globe of the roughly 16,700 satellites in CelesTrak’s active list, each worked out in your browser with SGP4, next to the real Moon, Sun and planets. Pick any satellite, share a location, and its panel lists the naked-eye passes over the next 48 hours. A handful of stations and well-known satellites, such as the ISS, Tiangong and Hubble, also have pass pages that look five days ahead. Brightness is an estimate based on the typical magnitude for that kind of satellite. The Starlink train page lists the next three days of passes for the newest batch with a brightness tag, or shows the next Starlink launch when no train is up. Pass rows, train passes and launches have an Add to calendar button. It’s free and needs no account. Ads appear on blog posts only. It suits people who want to see where everything is, on an Earth and star field built from NASA imagery, and follow the ISS, Hubble and Starlink.

How do the trackers compare side by side?

“Not listed” means we found no mention of the feature in the sources below. It doesn’t mean the site lacks it.

Tracker	Live view	Passes for your location	Alerts	Starlink trains	Debris, re-entries, close approaches	App
n2yo	Live map	Yes, visible and radio passes	Email and SMS	Starlink category to browse	Debris and rocket bodies tracked	Not listed
Heavens-Above	Sky chart for each pass	Yes	Calendar entries in the Android app	Not listed	Not listed	Android
satellitemap.space	3D globe	Yes	Email for Starlink trains	Starlink by generation	Re-entries, decay, close approaches	iOS
KeepTrack	3D globe	Not listed	Not listed	Not listed	Breakup simulator, debris screening, 64,000+ objects	Runs in the browser
Orbital Radar	3D globe	Yes	Alerts listed, including close encounters	Trains on the globe	Tracked debris, re-entry tracker	No app needed, AR in the browser
azmth.space	3D globe	Yes	None, per its own page	Detects new trains	Not listed	None, per its own page
FindStarlink	List of times for a place	Starlink only	Remind me, in the iPhone app	Its whole purpose	Not listed	iPhone
Spot the Station	2D and 3D location views, in the app	ISS only	Sign-up alerts and app notifications	Not listed	Not listed	iOS and Android
WatchSat	3D globe with Moon, Sun and planets	Yes, any satellite you pick	Calendar reminders; email alerts not on yet	Yes, with the next launch when none is up	None	None; add to home screen

Why do the object counts differ so much?

n2yo shows about 34,000 objects, KeepTrack’s features page says 64,000+, satellitemap.space covers 30,000+, azmth checks 15,000+ and WatchSat draws about 16,700. They are different lists. The larger ones include rocket bodies and debris, and WatchSat counts active satellites only. Compare a tracker’s number with what it says it counts, and see how many satellites are in orbit for the definitions.

What doesn’t WatchSat do yet?

Plenty, and several of these are done well elsewhere in this guide.

Debris. The globe draws active satellites only. Spent rocket stages and fragments aren’t shown, so n2yo, satellitemap.space, KeepTrack and Orbital Radar are the places to look. Our post on how much debris is in orbit has the numbers.
Re-entries. We have a post that explains them, but no tracker that predicts when an object will come down. Orbital Radar has one.
Close approaches. We show no conjunction data. satellitemap.space and KeepTrack cover it.
Alerts. ISS email alerts are built but switched off. Today you can add a pass, a Starlink train or a launch to your calendar with a reminder.
An app. WatchSat is a website. You can add it to your home screen, but it doesn’t work offline yet.
Filters. You can show Starlink, OneWeb, navigation, space stations or the rest. There is no filter by country, operator or launch date, which satellitemap.space and KeepTrack have.
Pass detail. Passes come with a compass direction, peak height and brightness estimate, but no sky chart for each pass the way Heavens-Above has.
What was that? We have no tool that takes a time and place and names the satellite you saw. azmth and Orbital Radar do.
Phone AR. Live Sky AR points your phone at the sky using its compass and motion sensors. We have tested it with simulated sensor readings, not yet on enough real phones, so treat it as experimental.

Keep reading

How to spot the ISS tonight for what to look for once a tracker has given you a time.
What is a TLE? for the data most of these trackers start from.
How many satellites are in orbit? for why the counts above disagree.

Sources

The pages and listings behind the claims above, as of October 13, 2026 unless a year is given.

n2yo, satellite page, object count, June 19, 2026, database, alerts help, Space Station notifications, API and widgets; Space.com, Introducing Space.com’s New Satellite Tracker from N2YO
Heavens-Above, Observing Satellites and mobile apps; Universe Today, How to Spot and Track Satellites
Gigazine, review of satellitemap.space, July 15, 2026; satellitemap.space, info; Apple App Store, SatelliteMap
KeepTrack, Why KeepTrack?, operations centers, Find Satellite, Next Launches, Debris Screening and source code
Orbital Radar, trackers, re-entry tracker, Skylens, press page and what is that light in the sky
azmth.space, What was that?, data and its own comparison; Product Hunt, azmth space
FindStarlink, site and reviews; Apple App Store, Find Starlink Satellites; KTNV, Starlink satellites visible from Spring Valley area, tracker says
NASA, Spot the Space Station Over Your Backyard With New NASA Service, 2012, and Look Up! New NASA App Helps Stargazers Spot Space Station, 2023; Space.com, Want to See the Space Station? NASA Text Messages Tell You How, 2012, and Track the ISS with NASA’s new Spot the Station mobile app, 2023; Apple App Store, Spot the Station
CelesTrak, active satellite element sets, the list behind WatchSat’s count

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