How to track the world's ships for free
AIS transponders broadcast every large vessel's position. Here's how to read the firehose.
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Every vessel over 300 tons broadcasts its identity, position, course and cargo destination via AIS. That data is collected by coastal receivers and satellites — and much of it is free to browse.
Open dashboards let you watch the Red Sea rerouting in near-real time, spot 'dark' vessels that switch transponders off in sensitive areas, and follow grain corridors out of contested ports.
The limits matter too: AIS is self-reported and can be spoofed. Analysts cross-check with satellite imagery before drawing conclusions.
Why it matters
Shipping data is the closest thing to a real-time sensor for the world economy — and it's open to anyone.
What to watch next
Growing use of AIS spoofing around sanctioned-oil 'shadow fleets'.