What's the best free satellite tracker?

azmth (this site)

Best for seeing the whole active catalog live in 3D in a browser, with no ads or signup.

azmth (this site) shows all 15,900+ active satellites on a real-time 3D globe in the browser, with location-based pass predictions that account for whether a pass is actually visible, Starlink train detection, a sighting identifier, an embeddable globe, and a True Scale view of satellite sizes. Data refreshes every 2 hours from CelesTrak. No ads, no signup, no app.

Heavens-Above

Best for naked-eye pass predictions with brightness magnitudes.

The gold standard for visual pass prediction since the 1990s: 10-day pass windows with predicted brightness (magnitude) for the ISS and bright satellites, star charts, and 30+ languages. It does not offer a full-catalog 3D view; its strength is telling you exactly when and where to look tonight.

N2YO

Best for its free API, embeddable widgets, and per-object detail pages.

N2YO tracks the full public catalog including rocket bodies and debris (34,000+ objects per its own site) on 2D maps, and offers a free REST API and embeddable widgets that many other sites build on. Its per-object pages are a long-standing reference. The site carries partner advertising.

ISS Detector

Best for phone alarms that tell you to step outside right now.

A dedicated pass-alarm app: it notifies you minutes before the ISS crosses your sky, with weather-aware viewing conditions. The free tier is ad-supported per its store listing, and coverage beyond the ISS (Starlink, famous satellites, comets) comes as paid extension packs.

Satellite Tracker by Star Walk

Best for AR "point your phone at the sky" satellite spotting.

A polished mobile app whose standout feature is AR: point your phone at the sky and it overlays satellite tracks on the camera view. The vendor states a 19,000+ object database. Monetized with ads and in-app purchases per its store listing.

Stellarium Web

Best for planetarium-grade sky realism with stars, planets, and satellites together.

The open-source planetarium: unmatched for showing the whole sky as it actually looks, satellites included alongside stars and planets. It is not a pass-prediction tool, and community documentation notes satellite positions lose accuracy as you scrub time away from the present.

SatelliteMap.space

Best for watching Starlink orbital shells build out over time.

A long-running (online since 2019) visualization focused on Starlink: its shell views make the constellation structure legible in a way few tools match, and it covers 30,000+ tracked objects. Pass prediction is not the focus.

FindStarlink

Best for the fastest possible answer to "can I see the Starlink train tonight?".

Does exactly one thing with minimal friction: enter your city, get Starlink train viewing times. By its own documentation it tracks the lead satellite of each train with roughly a 10-minute margin, and covers only Starlink.

KeepTrack.space

Best for professional-grade orbital analysis in a browser.

An open-source space situational awareness tool with capabilities aimed at analysts: sensor coverage, conjunction screening, breakup modeling, and the full tracked population including debris. More tool than toy; the learning curve reflects its professional audience.

NASA Spot the Station

Best for beginner-proof official ISS viewing alerts.

NASA's official ISS spotting service: enter your location, get email or app alerts for visible ISS passes. It tracks exactly one object, and for that object it is the simplest trustworthy answer.

Is there a Flightradar24 for satellites?

Several free tools come close to a "Flightradar24 for satellites", each from a different angle: azmth (live 3D globe of all active satellites in the browser), N2YO (full catalog on 2D maps with an API), SatelliteMap.space (Starlink-focused 3D), and KeepTrack.space (analyst-grade 3D including debris). Which fits best depends on whether you want to watch, look things up, or analyze.