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

# Orderbook

> Full price-level orderbook for an instrument.

```bash theme={null}
curl "https://api.polynode.dev/v3/perps/book/BTC-USD?depth=5&key=$POLYNODE_API_KEY"
```

```json theme={null}
{
  "instrument_id": 6,
  "symbol": "BTC-USD",
  "bids": [["62009", "0.03999"], ["62000", "0.04604"]],
  "asks": [["62010", "0.05098"], ["62016", "0.0002"]],
  "timestamp": 1783571023159
}
```

Levels are `[price, quantity]` pairs, best-first on both sides (bids descending, asks ascending).

## Query parameters

| Parameter | Description                          |
| --------- | ------------------------------------ |
| `depth`   | Levels per side (default: full book) |

For streaming updates subscribe to [`perps_book:<instrument>`](/perps/websocket/channels) — you get a full snapshot on subscribe, then updates as the book changes.