eth_subscribe - Validation Cloud

Subscribes to real-time events over WebSocket and returns a subscription ID that is attached to every notification. This method will use 20 Compute Units and each notification delivered on the subscription will use 10 Compute Units regardless of size.

WebSocket connections on Hyperliquid are served by nanoreth, the HyperEVM archive client. newHeads and logs subscriptions are supported. newPendingTransactions is accepted but never delivers events, because nanoreth has no mempool; do not rely on it.

Reference: Here

Parameters

subscription name - string - The type of event you want to subscribe to (newHeads, logs). This method supports the following subscription types:

newHeads - Fires a notification each time a new header is appended to the chain, including chain reorganizations.
logs - Returns logs that are included in new imported blocks and match the given filter criteria.

data - object - (Optional) - Arguments such as an address, multiple addresses, and topics. Note, only logs that are created from these addresses or match the specified topics will return logs.

// newHeads
params: ["newHeads"]

// logs from one contract
params: ["logs", {"address": "0x5555555555555555555555555555555555555555"}]

Returns

result - string - Hex encoded subscription ID. This ID will be attached to all received events and can also be used to cancel the subscription using eth_unsubscribe.

// Result
{"id":1,"result":"0x9a52eeddc2b289f985c0e23a7d8427c8","jsonrpc":"2.0"}

//Example (newHeads)
{
  "jsonrpc": "2.0",
  "method": "eth_subscription",
  "params": {
    "subscription": "0x9a52eeddc2b289f985c0e23a7d8427c8",
    "result": {
      "number": "0x2e2f25e",
      "hash": "0xfcc6c301f189ad5f3ae6d7678918c1e16268987e723be01bfd058a66559b2377",
      "parentHash": "0x6ef05b0441b71f2a57917c4603f3a246141896f11d7a1856a8a9672a28178878",
      "timestamp": "0x6ace13d8",
      "gasLimit": "0x2dc6c0",
      "gasUsed": "0x89c0c",
      "baseFeePerGas": "0x5f5e100",
      "miner": "0x0000000000000000000000000000000000000000",
      "transactionsRoot": "0xd4dc808b8a3e85d7bf8d051d7ecb896bf1b909f0ceeb231f5b774a40cadb22ae",
      "receiptsRoot": "0xefb0c21ecd3eb07f8b227b25f8248e944bfd58fe7be525bf41b268f8c72f92f1"
    }
  }
}

wscat -c wss://mainnet.hyperliquid.validationcloud.io/v1/wss/<YOUR_API_KEY_HERE>/evm
{"jsonrpc":  "2.0",  "id":  1,  "method":"eth_subscribe","params":["newHeads"]}
{"jsonrpc":"2.0","result":"0x5302037dae412a3454143512a3c7617b","id":1}