Real-time crypto prices.
One free WebSocket.

const ws = new WebSocket("wss://aeonfeed.com/ws");

ws.onopen = () => {
  ws.send(JSON.stringify({ op: "subscribe", channels: ["ticker:BTCUSDT"] }));
};

ws.onmessage = (e) => {
  const msg = JSON.parse(e.data);
  if (msg.type === "ticker" || msg.type === "snapshot") {
    for (const q of msg.data) console.log(q.ex, "bid", q.b, "ask", q.a);
  }
};

# pip install websockets
import asyncio, json, websockets

async def main():
    async with websockets.connect("wss://aeonfeed.com/ws") as ws:
        await ws.send(json.dumps({"op": "subscribe", "channels": ["ticker:BTCUSDT"]}))
        async for raw in ws:
            msg = json.loads(raw)
            if msg["type"] in ("ticker", "snapshot"):
                for q in msg["data"]:
                    print(q["ex"], "bid", q["b"], "ask", q["a"])

asyncio.run(main())

// tokio-tungstenite = { version = "0.24", features = ["native-tls"] }
use futures::{SinkExt, StreamExt};
use tokio_tungstenite::{connect_async, tungstenite::Message};

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let (mut ws, _) = connect_async("wss://aeonfeed.com/ws").await?;
    ws.send(Message::text(r#"{"op":"subscribe","channels":["ticker:BTCUSDT"]}"#)).await?;
    while let Some(msg) = ws.next().await {
        if let Message::Text(t) = msg? {
            println!("{t}");
        }
    }
    Ok(())
}

npx wscat -c "wss://aeonfeed.com/ws?subscribe=ticker:BTCUSDT"

curl https://aeonfeed.com/v1/ticker/BTCUSDT