Node.js

npm install ws

import WebSocket from "ws";

const KEY = "mts_live_YOUR_KEY";
const CHANNELS = ["metar.obs.eglc", "metar.obs.rksi"];

function connect() {
    const ws = new WebSocket(
          `wss://stream.metar.ws/v1/ws?key=${encodeURIComponent(KEY)}`,
        );

    ws.on("message", (buf) => {
          const msg = JSON.parse(buf.toString());
          switch (msg.type) {
            case "ack":
                      console.log("connected:", msg.plan, msg.limits);
                      ws.send(JSON.stringify({ action: "subscribe", channels: CHANNELS }));
                      break;
            case "publication":
                      console.log(`${msg.data.station}: ${msg.data.temp_c}°C (${msg.data.report_time})`);
                      break;
            case "error":
                      console.error("error:", msg.code, msg.channel ?? "");
                      break;
          }
    });

    ws.on("close", () => setTimeout(connect, 3000)); // reconnect loop
    ws.on("error", (e) => console.error("ws error:", e.message));
}

connect();