> ## Documentation Index
> Fetch the complete documentation index at: https://api.docs.rocketfi.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Orderbook

> Real-time order book updates for a single instrument (`SubscriptionKind::Orderbook`).

Open the **WSS** URL for your environment with path **`/ws`** (see [Environments](/guides/environments)), then subscribe payload **`Orderbook`** + **`instrumentId`**. For ping and errors, see [Public WebSocket streams](/guides/ws-public).