Live order books on Polymarket and Predict.fun

import WebSocket from "ws";
import { createHash, createHmac } from "node:crypto";

const venue = "polymarket"; // or "predictfun", if enabled for your organisation
const asset = process.env.BRAVADO_ASSET_ID;
const key = process.env.BRAVADO_API_KEY;
const secret = process.env.BRAVADO_API_SECRET;
if (!asset || !key || !secret) throw new Error("Set asset ID, API key and secret");
const path = `/stream/${venue}/partner`;
const timestamp = String(Date.now());
const payload = [timestamp, "GET", path, createHash("sha256").update("").digest("hex")].join("\n");
const signature = createHmac("sha256", secret).update(payload).digest("hex");
const ws = new WebSocket(`wss://partner-api.bravadotrade.com${path}`, {
  headers: {
    "X-BRAVADO-API-KEY": key,
    "X-BRAVADO-TIMESTAMP": timestamp,
    "X-BRAVADO-SIGNATURE": signature,
  },
});
ws.on("open", () => ws.send(JSON.stringify({
  op: "sub",
  streams: [`book:${asset}`],
})));
ws.on("message", data => {
  const frame = JSON.parse(data.toString());
  if (frame.type === "error") {
    console.error(frame.code, frame.message);
    return;
  }
  if (frame.channel !== "book") return;
  if (frame.type === "snapshot" || frame.type === "delta") {
    // Both frame types carry complete sides: replace your local book.
    console.log(frame.asset, frame.seq, frame.bids, frame.asks);
  } else if (frame.type === "status") {
    console.log(frame.state, frame.reason);
  }
});
ws.on("error", error => console.error(error.message));
const stop = setTimeout(() => ws.close(), 30_000);
ws.once("close", () => clearTimeout(stop));