The hazards your users report, and everyone else’s, on one stream.

curl -X POST https://api.cudatus.com/v1/events \
  -H "Authorization: Bearer $RELAY_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "type": "congestion",
    "lat": 45.7300,
    "lon": 4.8400,
    "severity": "medium",
    "road_ref": "A7",
    "description": "Queue building southbound"
  }'

const API = "https://api.cudatus.com";

// on your server — the key stays here
const { ticket } = await fetch(`${API}/v1/stream/tickets`, {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.RELAY_KEY}` },
}).then((r) => r.json());

// in the browser — a ticket, never the key
const stream = new EventSource(
  `${API}/v1/stream?lat=48.8698&lon=2.3078&radius=8000&ticket=${ticket}`,
);

stream.addEventListener("snapshot", (e) => replaceAll(JSON.parse(e.data).events));

stream.addEventListener("event", (e) => {
  // the delta is an envelope: created | updated | expired
  const { change, event } = JSON.parse(e.data);
  change === "expired" ? drop(event.event_id) : upsert(event);
});

// we always close on schedule; the ticket died long before
stream.addEventListener("bye", () => reconnectWithAFreshTicket());

A correct client owes the wire three things — treat every delta as an upsert, drop an event yourself when its deadline passes, and mint a fresh ticket after a bye. The streaming contract states each of them.

• Telematics platform editors

  One POST, one stream

  You run the platform a few hundred fleets log into, you have an API and you have developers.

  Your boxes already detect what Relay wants — harsh braking, prolonged immobilisation outside a delivery stop, impact detection. The raw material is on your servers; what it costs you is one HTTP call. We never ask for trajectories, only the point events you already derive.

• Navigation and mobility apps

  Subscribe and apply deltas

  You put a route in front of a driver, and a hazard on it is worth more the earlier it lands.

  Subscribe to a disc around a position and apply the deltas — one stream, one contract, no per-source integration. An itinerary is covered by subscribing discs along it, each one the same call.

  What your driver sees

• Road operators and public authorities

  DATEX II in, JSON out

  You already publish DATEX II, and you already asked whether we speak it.

  DATEX II in, JSON out. We consume the European standard and serve a real-time developer API over it — we are not replacing it and not competing with it. Your feed is brought up as a connector; the French national feed runs on one already.

  The feeds already connected

• Fleet managers

  Through your platform

  A truck stuck behind an accident is a missed delivery slot, and a detour is not trivial at 40 tonnes.

  Through the telematics platform you already use, not through us. A fifty-truck haulier has no development team and should not need one: when your platform integrates Relay, your fleet gets the network with nothing to build on your side.

• Carmakers

  Integration programme

  You have millions of connected vehicles giving data to a supplier who competes with you on navigation.

  The reciprocity is the argument: what your fleet publishes comes back as every other participant's events, instead of funding a service you then buy back. Homologation, functional safety and cybersecurity review set this cycle in years — an integration programme rather than an API key, and the wire contract is frozen precisely to survive that timescale.

  The reciprocity argument