Order Entry — Modify Order - QFEX API Documentation

Orders can be modified over WebSocket.
Only price, quantity, take_profit, and stop_loss may be changed.

You must specify the order’s order_id (UUID v4).
You must specify the symbol.
You must specify the side.
You must specify the order_type.
client_order_id cannot be used for modifies.

1) Authenticate

Send this immediately after you connect:

{ "type": "auth", "params": { "hmac": { "public_key": "qfex_pub_xxxxx", "nonce": "c0ffee...", "unix_ts": 1760545414, "signature": "5f2e..." } } }

2) Modify Order

{
  "type": "modify_order",
  "params": {
    "order_id": "510333ac-3f7b-4d88-934a-4396d48824cc",
    "symbol": "AAPL-USD",
    "side": "BUY",
    "quantity": 2,
    "price": 200,
    "take_profit": 200,
    "stop_loss": 150
  }
}

Parameters

Field	Type	Required	Description
`order_id`	string	✅	UUID v4 of the order to modify.
`symbol`	string	✅	The market symbol (e.g. `AAPL-USD`).
`side`	enum	✅	Must match the original order’s side. See OrderDirection.
`order_type`	enum	✅	Must match the original order’s type. See OrderType.
`quantity`	number	Optional	New order quantity. Must respect symbol lot size, min, and max constraints.
`price`	number	Optional	New price for limit/ALO orders. Ignored for market orders. Must respect tick size and price bands.
`take_profit`	number	Optional	Updated take-profit price. Set `0` if unused.
`stop_loss`	number	Optional	Updated stop-loss price. Set `0` if unused.

⚠️ Notes:

Only price, quantity, take_profit, and stop_loss may be modified.

client_order_id cannot be used for modifies.

The order_id changes on modification. The response will contain a new order_id. The old order_id is replaced. This is because multiple in-flight amends are not currently supported.

Modifications that would cause an invalid state (e.g. reducing below partially filled quantity) will be rejected with OrderStatus codes such as CANNOT_MODIFY_PARTIAL_FILL or CANNOT_MODIFY_NO_SUCH_ORDER.

Sample Code

# Python (websocket-client)
import json, websocket

API_KEY = "YOUR_API_KEY"

def send(ws, obj): ws.send(json.dumps(obj))

def on_open(ws):
    # Authenticate
    # https://docs.qfex.com/websocket/channels/trade/authenticate#how-it-works
    send(ws, {"type": "auth", "params": { "hmac": { "public_key": "qfex_pub_xxxxx", "nonce": "c0ffee...", "unix_ts": 1760545414, "signature": "5f2e..." }}})
    # Modify order
    send(ws, {
        "type": "modify_order",
        "params": {
            "order_id": "510333ac-3f7b-4d88-934a-4396d48824cc",
            "symbol": "AAPL-USD",
            "side": "BUY",
            "order_type": "LIMIT",
            "quantity": 2,
            "price": 200,
            "take_profit": 200,
            "stop_loss": 150
        }
    })

ws = websocket.WebSocketApp(
    "wss://trade.qfex.com?api_key=YOUR_API_KEY",
    on_open=on_open,
    on_message=lambda _, m: print("Message:", m)
)
ws.run_forever()

// Node.js (ws)
import WebSocket from "ws";
const ws = new WebSocket("wss://trade.qfex.com?api_key=YOUR_API_KEY");
const API_KEY = "YOUR_API_KEY";

ws.on("open", () => {
  // Authenticate
  ws.send(JSON.stringify({ type: "auth", params: { api_key: API_KEY } }));
  // Modify order
  ws.send(
    JSON.stringify({
      type: "modify_order",
      params: {
        order_id: "510333ac-3f7b-4d88-934a-4396d48824cc",
        symbol: "AAPL-USD",
        side: "BUY",
        order_type: "LIMIT",
        quantity: 2,
        price: 200,
        take_profit: 200,
        stop_loss: 150,
      },
    })
  );
});

ws.on("message", (msg) => console.log("Message:", msg.toString()));

// Go (gorilla/websocket)
package main

import (
	"log"
	"github.com/gorilla/websocket"
)

func mustWriteJSON(c *websocket.Conn, v any) {
	if err := c.WriteJSON(v); err != nil { log.Fatal("write:", err) }
}

func main() {
	c, _, err := websocket.DefaultDialer.Dial("wss://trade.qfex.com?api_key=YOUR_API_KEY", nil)
	if err != nil { log.Fatal("dial:", err) }
	defer c.Close()

	// Authenticate
	mustWriteJSON(c, map[string]any{
		"type": "auth",
		"params": map[string]any{"hmac": map[string]any{"public_key": "qfex_pub_xxxxx", "nonce": "c0ffee...", "unix_ts": 1760545414, "signature": "5f2e..."}}
	})

	// Modify order
	mustWriteJSON(c, map[string]any{
		"type": "modify_order",
		"params": map[string]any{
			"order_id":           "510333ac-3f7b-4d88-934a-4396d48824cc",
			"symbol":             "AAPL-USD",
			"side":               "BUY",
      "order_type":         "LIMIT",
			"quantity":           2,
			"price":              200,
			"take_profit":        200,
			"stop_loss":          150,
		},
	})
}

// Java (OkHttp WebSocket)
import java.util.concurrent.TimeUnit;
import okhttp3.*;

public class ModifyOrderWs {
  public static void main(String[] args) {
    OkHttpClient client = new OkHttpClient.Builder()
        .pingInterval(20, TimeUnit.SECONDS).build();

    Request req = new Request.Builder()
        .url("wss://trade.qfex.com?api_key=YOUR_API_KEY").build();

    WebSocketListener li = new WebSocketListener() {
      @Override public void onOpen(WebSocket ws, Response r) {
        // Authenticate
        ws.send("{\"type\": \"auth\", \"params\": { \"hmac\": { \"public_key\": \"qfex_pub_xxxxx\", \"nonce\": \"c0ffee...\..\", \"unix_ts\": 1760545414, \"signature\": \"5f2e...\" }}}");

        // Modify order
        ws.send("{\"type\":\"modify_order\",\"params\":{\"order_id\":\"510333ac-3f7b-4d88-934a-4396d48824cc\",\"symbol\":\"AAPL-USD\",\"side\":\"BUY\",\"order_type\":\"LIMIT\",\"original_quantity\":1,\"quantity\":2,\"price\":200,\"take_profit\":200,\"stop_loss\":150}}");
      }
      @Override public void onMessage(WebSocket ws, String text) {
        System.out.println(text);
      }
    };

    client.newWebSocket(req, li);
    try { Thread.sleep(Long.MAX_VALUE); } catch (InterruptedException ignored) {}
  }
}

Example Response

When an order is successfully modified, you receive the same order_response object as with add, but with status MODIFIED and a new order_id (the old one is replaced).

{
  "order_response": {
    "order_id": "88888888-4444-4444-4444-1234567890ab",
    "symbol": "AAPL-USD",
    "status": "MODIFIED",
    "quantity": 2.0,
    "price": 200.0,
    "take_profit": 200.0,
    "stop_loss": 150.0,
    "side": "BUY",
    "type": "LIMIT",
    "time_in_force": "GTC",
    "user_id": "0020ce8e-eaee-480e-8d7f-b9241d756ee5",
    "client_order_id": "",
    "quantity_remaining": 2.0,
    "trade_id": null
  }
}

​1) Authenticate

​2) Modify Order

​Parameters

​Sample Code

​Example Response

1) Authenticate

2) Modify Order

Parameters

Sample Code

Example Response