newFlashblockTransactions
Subscribe via eth_subscribe to receive each transaction as it is pre-confirmed into a Flashblock. Pass true as the second parameter to receive full transaction and log data.
Only available on Flashblocks WebSocket endpoints: wss://mainnet-preconf.base.org / wss://sepolia-preconf.base.org.
Requires base/base minimum client version v0.3.1.
Each subscription emits one item per WebSocket message, with events arriving roughly every 200ms. If your handler does heavy work per event, throttle or debounce it to avoid blocking.
Parameters
Section titled “Parameters”| Name | Type | Required | Description |
|---|---|---|---|
subscriptionType | string | Yes | Must be "newFlashblockTransactions". |
full | boolean | No | If true, each notification includes the full transaction object and associated logs. Defaults to false (minimal data only). |
Returns
Section titled “Returns”| Field | Type | Description |
|---|---|---|
result | string | Hex-encoded subscription ID. |
Example
Section titled “Example”Subscribe
Section titled “Subscribe”{"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newFlashblockTransactions"]}Subscribe (full data)
Section titled “Subscribe (full data)”{"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newFlashblockTransactions", true]}Subscription ID response
Section titled “Subscription ID response”{"jsonrpc": "2.0", "id": 1, "result": "0x1887ec8b9589ccad00000000000532da"}