# l2BookDiffSnapshot

{% hint style="info" %}
💧 New endpoint - this endpoint is not a part of original Hyperliquid API and is added by us for builder convenience.
{% endhint %}

### Overview

The `l2BookDiffSnapshot` endpoint returns full-depth L2 orderbook snapshots with `epoch`, `seq`, and `height` fields. This is the bootstrap endpoint for clients using the [`l2BookDiff`](/readme/websocket/l2bookdiff.md) WebSocket stream — fetch a snapshot here, then apply incremental diffs from the WebSocket to maintain a local orderbook.

**Key details:**

* Full-depth snapshots (all price levels)
* Includes `epoch`, `seq`, and `height` for diff stream synchronization
* Returns zstd-compressed msgpack

### Request

**Endpoint:** `POST /info`

**Single coin:**

```json
{
    "type": "l2BookDiffSnapshot",
    "coin": "ETH"
}
```

**Multiple coins:**

```json
{
    "type": "l2BookDiffSnapshot",
    "coins": ["ETH", "BTC"]
}
```

**All markets, perps only (default):**

```json
{
    "type": "l2BookDiffSnapshot"
}
```

**All markets, perps + outcomes:**

```json
{
    "type": "l2BookDiffSnapshot",
    "marketTypes": ["perp", "outcome"]
}
```

**Parameters:**

| Parameter     | Type      | Required | Description                                                                                                                                                                                                           |
| ------------- | --------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `coin`        | string    | No       | Single coin to fetch.                                                                                                                                                                                                 |
| `coins`       | string\[] | No       | Multiple coins to fetch.                                                                                                                                                                                              |
| `marketTypes` | string\[] | No       | All-markets only. Each entry is `"perp"`, `"spot"`, `"outcome"`, or the wildcard `"*"` (alone) for every type the server currently tracks. Omit for `["perp"]` (default). Rejected if combined with `coin` / `coins`. |

Omit both `coin` and `coins` to fetch all markets. Always returns full-depth snapshots.

### Response

**Headers:**

* `Content-Type: application/octet-stream`
* `Content-Encoding: zstd`

**Format:** Zstd-compressed msgpack `L2BookSnapshot`:

```json
{
    "coin": "ETH",
    "time": 1704067200000,
    "levels": [
        [
            {"px": "3245.5", "sz": "12.4", "n": 3},
            {"px": "3244.0", "sz": "8.7", "n": 5}
        ],
        [
            {"px": "3246.0", "sz": "6.2", "n": 2},
            {"px": "3247.5", "sz": "15.3", "n": 4}
        ]
    ],
    "height": 782007304,
    "epoch": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
    "seq": 42
}
```

### Field reference

| Field           | Type   | Description                                                       |
| --------------- | ------ | ----------------------------------------------------------------- |
| `coin`          | string | Market symbol                                                     |
| `time`          | number | Block timestamp (milliseconds since epoch)                        |
| `levels`        | array  | Tuple of `[bids, asks]`. Bids descending, asks ascending.         |
| `levels[][].px` | string | Price as decimal string                                           |
| `levels[][].sz` | string | Total size at this price level                                    |
| `levels[][].n`  | number | Number of orders at this level                                    |
| `height`        | number | Block height of this snapshot                                     |
| `epoch`         | string | Server epoch (UUID) — must match `epoch` in `l2BookDiff` messages |
| `seq`           | number | Per-coin sequence number — use as starting point for diff stream  |

### Bootstrapping the diff stream

1. Subscribe to [`l2BookDiff`](/readme/websocket/l2bookdiff.md) for your coin(s) — start buffering messages
2. Fetch this snapshot — note the `epoch` and `seq` for each coin
3. Discard buffered diffs where `epoch` doesn't match or `seq <= snapshot.seq`
4. Apply remaining diffs in order — the first should have `prev_seq == snapshot.seq`
5. If `epoch` changes or there's a seq gap, re-fetch this snapshot

### Common errors

* **400**: Invalid `coin`/`coins` parameter
* **403**: Permission denied - check API key
* **404**: No snapshot available yet
* **429**: Rate limit exceeded


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.hydromancer.xyz/readme/rest-api/market-data/l2bookdiffsnapshot.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.