The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Open Waters AIS listing page.
Live AIS vessel traffic, streamed by bounding box, from open government feeds and volunteer receivers. Part of Open Waters. The public instance is ais.openwaters.io. A live map is at openwatersio.github.io/aiscast.
This is a beta. There is no SLA. Coverage is uneven. The terms for re-serving some sources are still unsettled (see Coverage). Live status and uptime history are at status.openwaters.io.
aisstream.io clients. aiscast speaks aisstream.io's protocol on wss://ais.openwaters.io/v0/stream: the same subscribe message, the same MessageType / MetaData / Message frames. Change the hostname and use your aiscast token as the APIKey. Existing code keeps working: aisstream-ts, the official Go/Python/JS examples, and signalk-aisstream.
Native API (full reference).
wss://ais.openwaters.io/v1/stream: send {"type":"subscribe","bbox":[[minLat,minLon,maxLat,maxLon]]} or {"type":"subscribe","mmsi":[368168720]} (or both). You receive one JSON event per decoded AIS message. Each event carries its source, station, receive time, raw sentence, and the decoded fields. Add "snapshot":true to get the last known messages for every vessel already tracked in the subscription first, then live traffic. Subscribing needs no token.GET https://ais.openwaters.io/v1/vessels?bbox=minLat,minLon,maxLat,maxLon (or ?mmsi=a,b,c): GeoJSON of every vessel currently in view. Each vessel carries its last position, name, type, course, speed, heading, flag, and when and from where aiscast last heard it, plus IMO number, call sign, destination, ETA, draught, length, and beam once its static data has been heard. No token.GET https://ais.openwaters.io/v1/stations: every source aiscast is hearing, with message counts and age.AI assistants. https://ais.openwaters.io/mcp is an MCP (Model Context Protocol) server with five read-only tools: vessels by MMSI, vessels in an area, vessels near a point or another vessel, search by name, and coverage. No sign-in. Claude Code: claude mcp add --transport http open-waters-ais https://ais.openwaters.io/mcp. Claude.ai, ChatGPT, Cursor, and VS Code take the URL as a custom connector or mcp.json entry; setup for each is in the API reference. A token in an Authorization: Bearer header raises the anonymous limits.
Tokens. /v0/stream needs a token. A personal token is self-serve and never expires. Use the token page, or generate an Ed25519 keypair and POST https://ais.openwaters.io/v1/keys with {"pubkey":"<base64url public key>"}. The response is your token. It carries the personal tier: 2 streams, 50 messages/s, and a 20°×20° area. Feed data from the same token and it becomes a feeder token by itself.
Tiers and limits are in docs/limits.md. For more than the feeder tier, or for commercial use, write to hello@openwaters.io.
Events carry a source, so you can tell a live volunteer receiver from a government feed or an aggregate. synthesized: true marks messages that aiscast re-encoded from a non-NMEA source.
If you run an AIS receiver, send its data here. aiscast re-serves it to everyone, deduplicates it against the open feeds and every other station, and forwards it to AISHub as part of our reciprocal feed. Only volunteer receptions go to AISHub, and aiscast never relays public feeds there, per their terms. The terms for contributing are the contributor agreement.
AIS-catcher ... -Q wssmqtt://x:<token>@ais.openwaters.io:443/v1/stream MSGFORMAT NMEA. Each message is sent as it is decoded, over MQTT on the same WebSocket address the JSON stream uses. Your data appears as source: station:<station id>. Ask for a named station with higher limits. AIS-catcher's HTTP output works too: -H https://ais.openwaters.io/v1/receive USERPWD x:<token> GZIP on INTERVAL 5 posts a batch every five seconds under the same station.-u udp.ais.openwaters.io 10110, docker-shipfeeder with host udp.ais.openwaters.io port 10110, or any NMEA forwarder sending plain !AIVDM / !AIVDO sentences (TAG blocks welcome). Your station appears as udp:<id>, a keyed hash of your address, never the address itself. If a sender's !AIVDO sentences identify the vessel, aiscast keys the station by that MMSI instead.udp.ais.openwaters.io:10110 in ais-forwarder (forward AIVDM and AIVDO). Or install the signalk-aiscast plugin. It needs no token. It shares what your receiver hears, and your own position, taken from the transponder or built from Signal K when an AIS transponder is not available. It shows aiscast traffic when you have no receiver.Your station page is the map with ?station=<your id>. It shows vessels heard, coverage extent, message counts, and how many messages another station heard first. GET /v1/stations/{id} returns the same numbers. Feeders get the deduplicated raw stream back on wss://ais.openwaters.io/v1/nmea.
| Source | Where | Freshness |
|---|---|---|
| Kystverket | Norwegian coast, 40–60 nm out | live |
| BarentsWatch | Norwegian EEZ, Svalbard, Jan Mayen (satellite + offshore receivers) | live |
| Fintraffic Digitraffic | Finnish waters | live |
| Volunteer receivers | wherever they are (Buzzards Bay / Vineyard Sound as of the first station) | live |
| AISHub aggregate | worldwide terrestrial, ~50k vessels | about a minute behind |
| aisstream.io | worldwide, when it is up | live, but frequently down |
/v1/stats reports each source's current delay from broadcast to arrival (delay.p50 and delay.p99, in seconds).
Every event names the source it came from. docs/policy.md lists the sources this project leaves out on purpose, and why.
Licensing is per source. aiscast does not relicense the aggregate. aiscast re-serves each event under the terms of the source it came from. That is why source is on every event, every vessel, and every archived hour, and why every /v1 event carries a license tag and an attribution credit line. Every attribution opens with "Open Waters AIS (https://openwaters.io/ais/)"; sources with their own terms add their credit after it. If you display or redistribute the data, display the attribution message included with each event. /v1/vessels carries the same credits as a top-level attribution member on the feature collection, one entry per source present. The table below is the same information as reference.
| Source | License | What you must do |
|---|---|---|
| Kystverket | NLOD 2.0 | Credit: "Contains data under the Norwegian licence for Open Government data (NLOD) distributed by the Norwegian Coastal Administration." NLOD is not sublicensable, so it binds you directly. |
| BarentsWatch | NLOD per the BarentsWatch API terms | Credit: "Data delivered by BarentsWatch." It is the same AIS Norge data as Kystverket, so the Kystverket credit applies too. |
| Fintraffic Digitraffic | CC BY 4.0 | Credit: "Source: Fintraffic / digitraffic.fi, license CC 4.0 BY." |
| Volunteer receivers | The contributor agreement dedicates receptions to the public domain under CC0 and publishes the aggregate under ODbL | Credit "Open Waters AIS (https://openwaters.io/ais/)". Individual receptions are CC0. The aggregate carries ODbL. |
| AISHub aggregate | AISHub membership: contributors "are allowed to use the aggregated data for free". No stated restriction on publication or commercial use | Credit "AISHub" and keep the source: aishub value on the data. |
| aisstream.io | no published terms | Best effort, may disappear. source: aisstream. |
aiscast's own code is MIT. aiscast identifies UDP stations by a keyed hash instead of an address (a station that sends !AIVDO is keyed by that MMSI, and its position is in the data it shares). The archive keeps raw receptions per source, so the project can purge any source. docs/policy.md states the full position: what the contributor agreement says, the privacy rules, and how the project intends to fund itself without relicensing data.
Developers and operators: see CONTRIBUTING.md.