Open Waters AIS MCP server

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, and when and from where aiscast last heard it. 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":""}. 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.

Shortened. The full README is on GitHub.