aiscast

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.

Usage

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.

Contributing data

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 (preferred: authenticated, realtime, works behind any NAT): get a token at openwaters.io/ais/token (one click, stays in your browser), then 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.
• UDP (no token): AIS-catcher -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.
• Signal K: add a UDP target 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.

Coverage

/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 and attribution

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.