Live data feed

Endpoints

CORS is open on all of them. Current channel table version: 234eb0a69e6f.

Getting started

const socket = new WebSocket("wss://kels-telemetry-hub.sanis-c48.workers.dev/live");

// Signal ids are stable. Fetch the table once to map id -> name/unit/range.
const table = await (await fetch("https://kels-telemetry-hub.sanis-c48.workers.dev/api/signals")).json();
const byId = Object.fromEntries(table.signals.map((s) => [s.id, s]));

const latest = {};

socket.onmessage = (event) => {
  const msg = JSON.parse(event.data);

  if (msg.t === "snap" || msg.t === "delta") {
    // A delta carries ONLY what changed. Merge, never replace.
    Object.assign(latest, msg.v);

    const speed = latest[table.byName.Vehicle_Speed];
    const rpm = latest[table.byName.Engine_RPM];
    render(speed, rpm);
  }

  if (msg.t === "status" && !msg.car) {
    // The car stopped streaming. Show that -- do not keep painting old numbers.
    showOffline();
  }
};

Messages

{ "t": "snap", "seq": 1042, "ts": 1754668800123, "v": { "0": 6820, "1": 98.4 }, "age": { "0": 40, "1": 900 } }

{ "t": "delta", "seq": 1043, "ts": 1754668800173, "v": { "0": 6910, "7": 41 } }

{ "t": "status", "car": true, "since": 1754668790000, "viewers": 312, "carId": "kels-01" }

{ "t": "laps", "sessionId": 4, "laps": [{ "id": 118, "lap": 7, "time": 91.86, "sectors": [30.44, 31.19, 30.23], "states": [1, 2, 3] }] }

{ "t": "lap", "lap": { "id": 118, "lap": 7, "time": 91.86, "sectors": [30.44, 31.19, 30.23], "states": [1, 2, 3] } }

{ "t": "config", "track": "Circuit of the Americas", "event": "Round 4", "links": [{ "label": "Live stream", "url": "https://youtu.be/..." }] }

Things you can send us

• { "t": "ping", "id": 1 } — we reply { "t": "pong", "id": 1 }, so you can measure latency.
• { "t": "resync" } — asks for a fresh snapshot. Send this if seq ever skips a number, which means you missed an update.

Three things worth knowing

1. Deltas are partial. A message contains only what changed. Merge it into your copy of the state — do not replace.
2. Values are already scaled. Speed is km/h, tire temperatures are °C, tire pressures are kPa (not psi), power is kW. Battery power goes negative under regeneration.
3. Nothing is faked. If the car goes offline you get a status message rather than zeros. A channel that stops updating simply stops appearing in deltas — check its age rather than assuming it is current. The same rule holds in the lap table: a sector we could not resolve is null, never a guess.
4. Laps are amended after they are published. The lap time and the third sector both arrive a second or two after the line. Key on the lap's id and replace, rather than appending each message as a new row.

Channels

Ids are stable but are regenerated if the car's CAN database changes. Fetch /api/signals at startup rather than hardcoding them; the table below is the current state.