WebSocket

Real-time market data and user event streaming via WebSocket.

Subscription Types

Type	Data	Auth
`trades`	Real-time trades	No
`l2Book`	Order book updates	No
`bbo`	Best bid/offer	No
`candle`	Candlestick updates	No
`allMids`	All mid prices	No
`activeAssetCtx`	Asset context (funding, OI)	No
`userEvents`	User fills, liquidations	Yes
`userFills`	User trade fills	Yes
`userFundings`	User funding payments	Yes
`orderUpdates`	Order status changes	Yes
`notification`	System notifications	Yes
`webData2`	Extended web data	Yes
`activeAssetData`	User asset data (leverage, margin)	Yes

Protocol Details

Connection

wss://api.hyperliquid.xyz/ws     (mainnet)
wss://api.hyperliquid-testnet.xyz/ws  (testnet)

Ping/Pong

Hyperliquid uses app-level ping/pong (not WebSocket protocol-level):

Server sends: Ping (plain text)
Client must respond: {"method":"pong"}
Timeout: ~30 seconds without pong → disconnect

{"method":"subscribe","subscription":{"type":"trades","coin":"BTC"}}

Unsubscribe

{"method":"unsubscribe","subscription":{"type":"trades","coin":"BTC"}}

Message Format

All messages arrive as JSON with a channel wrapper:

{"channel":"trades","data":[{"coin":"BTC","side":"B","px":"97432.5","sz":"0.1","time":1234567890}]}

The SDK's ws_types.extractData() strips the outer wrapper — decode functions receive the data value directly.

SDK Usage

const Ws = hlz.hypercore.ws;
 
// The WS module provides subscription type definitions
// Actual WebSocket connection is managed by the terminal/CLI layer
// using websocket.zig for the transport

Thread Safety

WebSocket reads are blocking — run in a dedicated thread
Use shutdown(fd) to break out of a blocking read (for coin/interval switches)
Do not use SO_RCVTIMEO with TLS on macOS (causes segfaults)
Parse messages outside the lock, apply results under the lock