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

# Build with the Hyperliquid L2 Order Book

*Published May 11, 2026*

![Build with the Hyperliquid L2 Order Book](https://www.datocms-assets.com/86369/1780000650-04_build_with_the_hyperliquid_l2_order_book.jpg)

The Hyperliquid WebSocket API exposes Hyperliquid's `l2Book` channel at `wss://hypercore.goldrushdata.com/ws`, wire-equal to the public feed but with `coin` made optional and the per-IP subscription cap removed. A new [recipe page](/goldrush-hyperliquid/websocket-api/l2-book) shows how to turn that stream into the trading and analytics primitives most builders need.

## Why it's nice to work with

* **Complete snapshots, not diffs** - every message contains a full `[bids, asks]` tuple in best-first order with `px` / `sz` / `n` per level. No sequence numbers to track, no diff replay buffer, no REST snapshot to bootstrap.
* **Self-healing on packet loss** - drop a message or restart your process and the next tick arrives with the full book state, so your in-memory view is correct without reconciliation logic.
* **Wildcard coverage** - omit `coin` to stream every asset's book over a single subscription instead of fanning out one subscription per asset.

## What you can build

The recipe walks through four patterns end-to-end with TypeScript and Python code:

* **Top-of-book tracker** - read `bids[0]` and `asks[0]` from each message for a live ticker and spread.
* **Depth-weighted mid quote** - size-weight the first `K` levels per side for a fair-value mid that's robust to thin top-of-book liquidity.
* **Slippage estimator** - walk levels until cumulative `sz` covers the requested notional and return the size-weighted fill price.
* **Liquidity heatmap** - append each snapshot to a time-series store; because messages are complete, the heatmap rebuilds correctly from any contiguous slice of history.

[Learn more](https://goldrush.dev/docs/goldrush-hyperliquid/websocket-api/l2-book)