Where the data comes from

Why this page exists

Almost every "live tracker" hides where its numbers come from, which makes them impossible to judge. If a layer looks empty, is that a bug, a rate limit, or genuinely no data? Knowing the publisher and the limits answers that question immediately, and it tells you how much to trust a given layer.

Everything below is fetched from the upstream provider and cached before it reaches your browser. Nothing is scraped from a private or paid source.

Aviation

CelesTrak — satellites

CelesTrak publishes current two-line element sets derived from US Space Force general perturbations data. The app requests TLE sets per group and propagates them locally with SGP4, which means orbits are computed on your machine rather than fetched pre-baked. Groups used are stations, visual, gps-ops, glo-ops, galileo and geo, with starlink available as a dense extra.

Limits: keyless and generous, but the full active group is a multi-megabyte download and the server is frequently slow. The app caches TLEs for six hours because the orbits barely change in that window. If the satellite layer looks empty, the upstream server is almost certainly the cause rather than anything local.

OpenSky Network — live flights

A volunteer-run network of ADS-B receivers operated by the OpenSky Foundation, providing the most complete open picture of global air traffic available. It aggregates contributions from hundreds of receivers worldwide.

Limits: this is the single most important limit in the whole app. The REST API moved to requiring OAuth2 client credentials; anonymous access still functions but is heavily rate limited to roughly 400 credits per day and gives degraded coverage. Because the credit cost scales with the area queried, the app requests bounded regions rather than the whole planet at once. Without credentials it falls back to the keyless adsb.lol point API below.

adsb.lol — military aircraft and fallback flights

A free, key-free API mirroring open ADS-B, used for two things: the military aircraft filter, and as the fallback provider when OpenSky credentials are absent.

Limits: no key and no formal quota, but it is a small volunteer project. It only carries aircraft that are broadcasting and are within receiver coverage. It does not expose trace history, which is why 24-hour track history is only available where OpenSky can serve it.

Earth and environment

USGS — earthquakes

The United States Geological Survey aggregates seismometer networks worldwide and publishes detections continuously as GeoJSON. God’s Eye View shows a rolling 24-hour window and plots each event at its true depth inside the globe. Fetched directly by the browser, with no proxy in between.

Limits: keyless, no documented quota, and the feed is one of the most reliable on the internet. Coverage is uneven by nature: magnitude 2 and below only gets detected where instruments are dense, so Japan and California look busy and sparsely instrumented regions look quiet even when they are equally seismically active.

NASA FIRMS — active fires

The Fire Information for Resource Management System, using VIIRS thermal anomaly data from NOAA-20, NOAA-21 and Suomi-NPP, published as near-real-time active fire detections.

Limits: requires a free MAP_KEY from NASA. Detections are thermal anomalies, which means industrial flaring and agricultural burning appear alongside wildfires. That is a feature for analysis, but it means “fire” here is broader than “wildfire”.

Maritime and ground transport

AISStream — vessel positions

Ship positions from the Automatic Identification System, a VHF broadcast that ships transmit to announce themselves. AISStream brokers the WebSocket feed.

Limits: requires an API key. The important caveat is that AIS is voluntary and line-of-sight: coverage is dense on major shipping lanes and effectively empty at sea. A quiet ocean usually means nobody is broadcasting, not that nobody is there.

GTFS-Realtime — public transit

Seven operator feeds: MBTA, CapMetro, Metro Transit, HSL, OVapi, Entur and TransLink.

Limits: GTFS-Realtime is the standard for transit agencies and feeds are keyless, but each operator only publishes for its own network. There is no global transit feed, so the layer is city-by-city rather than worldwide.

GBFS — bikeshare

The General Bikeshare Feed Specification, used by roughly 30 operators worldwide. Published as a station list plus availability status.

Limits: keyless, but again strictly per-operator and usually per-city.

Mapping and routing

OpenStreetMap and Overpass API

The underlying map database, and the Overpass API used to query it for road geometry, installations and mapped cameras. Overpass is volunteer infrastructure and is genuinely free, which is why it carries a lot of this app.

Limits: public Overpass instances rate-limit aggressively and frequently return 429 under load or report a 521 from the origin. The app tries three mirrors in sequence and falls back to cached results, then degrades gracefully. This is the most common source of "traffic layers didn't load".

TomTom Traffic Flow

Optional real-time congestion vector tiles, decoded client-side. Without a key the traffic layer runs a clearly labelled simulation instead — useful for understanding the layer, useless for real conditions.

Limits: requires an API key. TomTok flow is commercial and metered.

OSRM / FOSSGIS — routing

OpenStreetMap Routing Machine, served by the FOSSGIS volunteer-run instances, computing the routes the Directions layer draws in 3D.

Limits: keyless and community donated, so it is best used for occasional requests rather than bulk routing.

Basemap, terrain and sky

Esri World Imagery and OpenStreetMap

The two default basemaps. Esri's ArcGIS tile service needs no key and gives high-resolution satellite imagery; OpenStreetMap is the automatic fallback if Esri tiles fail. Google Photorealistic 3D Tiles and Bing imagery are optional upgrades requiring keys.

Terrain

Quantised-mesh terrain from Mapterhorn's open elevation tilesets, with a bundled EGM96 geoid model as fallback so elevation reads correctly even where the terrain service is unavailable.

Bundled offline datasets

Several layers ship inside the app and never touch the network: 712 submarine cables and 1,917 landing points from TeleGeography (CC BY-NC-SA 3.0), 4,351 datacenters (ODbL 1.0), 704 dams (ODbL 1.0), 3,445 precomputed CCTV ground heights, and the Astronomy catalogues including Hipparcos bright stars, planets, galaxies, nebulae and clusters.

Licensing matters here: the submarine cable and infrastructure datasets are non-commercial, so the app as a whole is not usable for commercial redistribution without checking those terms.

What this means in practice

Three honest conclusions worth taking from this list:

1. An empty layer usually means an upstream limit, not a broken app. Every live source here is volunteer-run, academic or rate-limited.
2. Coverage is genuinely uneven. Aviation and AIS are dense near wealthy, instrumented infrastructure and sparse elsewhere. That is a property of the real world.
3. Most of it is free and open. The layers that need keys are the genuine commercial upgrades: full flight coverage, real traffic flow and photorealistic Google tiles.