blockSubscribe

Subscribe to receive notification anytime a new block is confirmed or finalized.

This subscription is considered unstable and is only available if the validator was started with the --rpc-pubsub-enable-block-subscription flag. The format of this subscription may change in the future.

This is an unstable RPC method that Helius does not support. This documentation is provided for reference only.

Endpoints

Websockets are available on mainnet and devnet with the following URLs:

• Mainnet wss://mainnet.helius-rpc.com/?api-key=<API_KEY>
• Devnet wss://devnet.helius-rpc.com/?api-key=<API_KEY>

Websockets have a 10-minute inactivity timer; implementing health checks and sending pings every minute is heavily recommended to keep the websocket connection alive.

Authorizations

api-key · string · required

Your Helius API key. You can get one for free in the dashboard.

Body

params · array · required

Hide properties

filter · string | object · required

Filter criteria for the logs to receive results by account type; currently supported:

• all - include all transactions in block
• A JSON object with the following field:
  • mentionsAccountOrProgram: <string> - return only transactions that mention the provided public key (as base-58 encoded string). If no mentions in a given block, then no notification will be sent.

config · object

Configuration object containing the following fields:

commitment · string

The commitment level for the subscription. Can be finalized, confirmed, or processed.

encoding · string

Encoding format for the transaction data.

transactionDetails · string

Level of transaction detail to return.

maxSupportedTransactionVersion · number

The max transaction version to return in responses.

showRewards · boolean

Whether to show rewards in the response.

Response

result · integer

Subscription id (needed to unsubscribe)

Notification Format

The notification will be an object with the following fields:

• slot: <u64> - The corresponding slot.
• err: <object|null> - Error if something went wrong publishing the notification otherwise null.
• block: <object|null> - A block object as seen in the getBlock RPC HTTP method.

Request

{
  "jsonrpc": "2.0",
  "id": "1",
  "method": "blockSubscribe",
  "params": [
    {
      "mentionsAccountOrProgram": "LieKvPRE8XeX3Y2xVNHjKlpAScD12lYySBVQ4HqoJ5op"
    },
    {
      "commitment": "confirmed",
      "encoding": "base64",
      "showRewards": true,
      "transactionDetails": "full"
    }
  ]
}

Response

{
  "jsonrpc": "2.0",
  "result": 0,
  "id": 1
}