Order Book WebSocket

Streams order book snapshots for a symbol whenever the book changes.

Event name	FETCH_ORDER_BOOK_CS_PRO
Connection	See Connection for handshake and namespace details.

Subscribe

Python

import socketio

sio = socketio.Client()

BASE_URL = "wss://ws.coinswitch.co/"
NAMESPACE = "/coinswitchx"          # exchange namespace
pair = "BTC,INR"                     # note BASE,QUOTE — comma, not slash

sio.connect(
    url=BASE_URL,
    namespaces=[NAMESPACE],
    transports="websocket",
    socketio_path="/pro/realtime-rates-socket/spot",
    wait=True,
    wait_timeout=3600,
)

sio.emit(
    "FETCH_ORDER_BOOK_CS_PRO",
    {"event": "subscribe", "pair": pair},
    namespace=NAMESPACE,
)

@sio.on("FETCH_ORDER_BOOK_CS_PRO", namespace=NAMESPACE)
def on_order_book(data):
    print("Order book update:", data)

sio.wait()

Java

import okhttp3.*;
import org.json.JSONObject;

String exchange = "coinswitchx";          // -> /coinswitchx namespace
String coinPair = "BTC,INR";              // BASE,QUOTE

OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
    .url("wss://ws.coinswitch.co/pro/realtime-rates-socket/spot/?EIO=4&transport=websocket")
    .build();

JSONObject subscribe = new JSONObject()
    .put("event", "subscribe")
    .put("pair", coinPair);

String namespaceFrame = "40/" + exchange + ",";
String subscribeFrame = "42/" + exchange + ",[\"FETCH_ORDER_BOOK_CS_PRO\"," + subscribe + "]";

WebSocket ws = client.newWebSocket(request, new WebSocketListener() { /* ... */ });
ws.send(namespaceFrame);
ws.send(subscribeFrame);

Go

import (
    "log"
    socketio "github.com/zishang520/socket.io-client-go/v2/client"
)

// socket.io-client-go is the most actively maintained Go client for
// Socket.IO v4 servers. Add it with:
//   go get github.com/zishang520/socket.io-client-go/v2

opts := socketio.DefaultOptions()
opts.SetTransports([]string{"websocket"})
opts.SetPath("/pro/realtime-rates-socket/spot")

sock := socketio.Connect("wss://ws.coinswitch.co/coinswitchx", opts)
defer sock.Close()

sock.On("connect", func(args ...any) {
    sock.Emit("FETCH_ORDER_BOOK_CS_PRO", map[string]any{
        "event": "subscribe",
        "pair":  "BTC,INR",
    })
})

sock.On("FETCH_ORDER_BOOK_CS_PRO", func(args ...any) {
    log.Println("update:", args)
})

select {} // block forever

Node.js

// npm install socket.io-client@^4
const { io } = require('socket.io-client');

const sock = io('wss://ws.coinswitch.co/coinswitchx', {
  path: '/pro/realtime-rates-socket/spot',
  transports: ['websocket'],
});

sock.on('connect', () => {
  sock.emit('FETCH_ORDER_BOOK_CS_PRO', { event: 'subscribe', pair: 'BTC,INR' });
});

sock.on('FETCH_ORDER_BOOK_CS_PRO', (data) => {
  console.log('update:', data);
});

Update payload

{
  "s": "BTC,INR",
  "timestamp": 1673255767122,
  "bids": [
    ["1471201.000000000000", "0.005870"],
    ["1470201.000000000000", "0.046770"]
  ],
  "asks": [
    ["1484400.000000000000", "0.022109"],
    ["1484500.000000000000", "0.000390"]
  ]
}

Field	Type	Description
s	string	Symbol in BASE,QUOTE form.
timestamp	integer	Snapshot time (Unix ms).
bids	array	Sorted descending. Each entry [price, quantity] (both strings).
asks	array	Sorted ascending. Each entry [price, quantity] (both strings).

Each push is a full snapshot, not a delta. Replace your local book on every event.