Connect
Open the socket, authenticate, keep it alive, reconnect cleanly.
Channels
The full channel and symbol matrix by venue family.
Stream The Hyperliquid Order Book
Theorderbook channel streams aggregated (L2) depth updates for core perp symbols such as BTC and ETH. Spot, HIP-3, and HIP-4 use venue-prefixed channels (spot_orderbook, hip3_orderbook, hip4_orderbook) with their own symbol shapes; Lighter is a separate venue family with lighter_orderbook and an order-level lighter_l3_orderbook.
L2 Book Streaming And L4 Book Streaming
Pick the depth by the downstream job, not by habit:| Need | Channel | What arrives |
|---|---|---|
| Aggregated depth (L2 book) | orderbook | Price levels with size, live or replayed |
| Order-level book (L4) | l4_diffs | Per-order book changes for local-state maintenance |
| Order events | l4_orders | Placements, fills, cancels, and status changes, including trigger orders |
| Fill stream | trades | Executions as they happen |
Replay History On The Same Socket
Replay sends historical data over the WebSocket at a controlled speed, in original sequence. The command names the channel, symbol, window, and speed:replay_started, a replay_snapshot baseline, ordered historical_data messages, and replay_completed at the end of the window. gap_detected marks missing intervals so the client can stop or rebuild instead of silently corrupting local state. Controls are replay.pause, replay.resume, replay.seek, and replay.stop. Full command and event shapes live in WebSocket replay and the message schema.
Replay Speed And Subscriptions By Plan
| Plan | Max replay speed | Max subscriptions |
|---|---|---|
| Free | 10x | 10 |
| Build | 50x | 500 |
| Pro | 100x | 3,000 |
| Scale | 300x | 20,000 |
| Enterprise | from 500x | Unlimited |
Low Latency You Can Measure
Latency intent deserves a number, not an adjective./v1/data-quality/latency returns current API, WebSocket, and freshness latency measurements per venue family, so a latency-sensitive client can check the live figure before and during a job instead of trusting marketing copy. Pair it with /v1/data-quality/status for per-family last_data_at and latency_ms.