> ## Documentation Index
> Fetch the complete documentation index at: https://docs.base.org/llms.txt
> Use this file to discover all available pages before exploring further.

# newFlashblockTransactions

> Subscribe to receive each transaction as it is pre-confirmed into a Flashblock. Only available on Flashblocks WebSocket endpoints.

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 receipt data.

<Info>
  This subscription requires a WebSocket-enabled RPC endpoint. The public Base endpoints (`mainnet.base.org`, `sepolia.base.org`) are HTTP only. Use a [node provider](/base-chain/node-operators/node-providers) such as Alchemy or QuickNode that offers WebSocket support for Base.
</Info>

<Note>
  Requires [base/base](https://github.com/base/base) minimum client version v0.8.0.
</Note>

<Warning>
  Each subscription emits **one item per WebSocket message**. Events arrive approximately every 200ms. If your handler performs heavy processing per event, throttle or debounce it to avoid blocking.
</Warning>

## Parameters

<ParamField body="subscriptionType" type="string" required>
  Must be `"newFlashblockTransactions"`.
</ParamField>

<ParamField body="full" type="boolean">
  If `true`, each notification includes the full transaction object with receipt fields embedded. Defaults to `false` (transaction hash only).
</ParamField>

## Returns

<ResponseField name="result" type="string">
  Hex-encoded subscription ID returned on subscribe.
</ResponseField>

## Notifications

Each notification is a standard `eth_subscription` message. The `params.result` field depends on the `full` parameter:

**`full: false`** — `result` is the transaction hash:

```json theme={null}
"0xe26de91f9037e903eefe70b28f613019253da603e67e0dbfe2f656dce5444311"
```

**`full: true`** — `result` is a transaction object with receipt fields embedded directly (no nested receipt sub-object). Verified live against `base/v0.9.0`:

<ResponseField name="type" type="string">Transaction type: `0x0` Legacy, `0x2` EIP-1559, `0x7e` Deposit.</ResponseField>
<ResponseField name="chainId" type="string">Chain ID (hex).</ResponseField>
<ResponseField name="nonce" type="string">Sender nonce (hex).</ResponseField>
<ResponseField name="gas" type="string">Gas limit (hex).</ResponseField>
<ResponseField name="maxFeePerGas" type="string">EIP-1559 max fee per gas (hex).</ResponseField>
<ResponseField name="maxPriorityFeePerGas" type="string">EIP-1559 max priority fee per gas (hex).</ResponseField>
<ResponseField name="to" type="string">Recipient address.</ResponseField>
<ResponseField name="value" type="string">ETH value transferred (hex).</ResponseField>
<ResponseField name="accessList" type="array">EIP-2930 access list.</ResponseField>
<ResponseField name="input" type="string">Transaction input data (hex).</ResponseField>
<ResponseField name="r" type="string">Signature r component.</ResponseField>
<ResponseField name="s" type="string">Signature s component.</ResponseField>
<ResponseField name="yParity" type="string">Signature parity (hex).</ResponseField>
<ResponseField name="v" type="string">Signature v value (hex).</ResponseField>
<ResponseField name="hash" type="string">Transaction hash.</ResponseField>
<ResponseField name="blockHash" type="null">Always `null` — transaction is pre-confirmed, not yet in a finalized block.</ResponseField>
<ResponseField name="blockNumber" type="string">Block number (hex) of the in-progress Flashblock.</ResponseField>
<ResponseField name="transactionIndex" type="string">Index within the block (hex).</ResponseField>
<ResponseField name="from" type="string">Sender address.</ResponseField>
<ResponseField name="gasPrice" type="string">Effective gas price (hex).</ResponseField>
<ResponseField name="gasUsed" type="string">Gas used by this transaction (hex). **Note:** changed from integer to hex string in v0.8.0.</ResponseField>
<ResponseField name="status" type="string">`0x1` for success, `0x0` for failure.</ResponseField>
<ResponseField name="cumulativeGasUsed" type="string">Total gas used in the block up to and including this transaction (hex).</ResponseField>
<ResponseField name="contractAddress" type="string | null">Address of the created contract, or `null`.</ResponseField>
<ResponseField name="logsBloom" type="string">Bloom filter of logs (hex).</ResponseField>
<ResponseField name="logs" type="array">Array of log objects emitted by this transaction.</ResponseField>

<Warning>
  `gasUsed` is a hex string (e.g. `"0x26132"`), not an integer. This changed in v0.8.0 — update any parsers that expect a numeric value.
</Warning>

## Example

<CodeGroup>
  ```json Subscribe theme={null}
  {"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newFlashblockTransactions"]}
  ```

  ```json Subscribe (full data) theme={null}
  {"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["newFlashblockTransactions", true]}
  ```

  ```json Subscription ID Response theme={null}
  {"jsonrpc": "2.0", "id": 1, "result": "0x1887ec8b9589ccad00000000000532da"}
  ```

  ```json Notification (full: false) theme={null}
  {
    "jsonrpc": "2.0",
    "method": "eth_subscription",
    "params": {
      "subscription": "0x1887ec8b9589ccad00000000000532da",
      "result": "0xe26de91f9037e903eefe70b28f613019253da603e67e0dbfe2f656dce5444311"
    }
  }
  ```

  ```json Notification (full: true) theme={null}
  {
    "jsonrpc": "2.0",
    "method": "eth_subscription",
    "params": {
      "subscription": "0x1887ec8b9589ccad00000000000532da",
      "result": {
        "type": "0x2",
        "chainId": "0x2105",
        "nonce": "0x34ed",
        "gas": "0x7a1200",
        "maxFeePerGas": "0x257ab3c",
        "maxPriorityFeePerGas": "0x419c7c",
        "to": "0x6211a3742cf9d3b6677ecc7fd9dd102ab101d8e2",
        "value": "0x0",
        "accessList": [],
        "input": "0x...",
        "r": "0xa7cd30d21c30d4d60d27073c8bbc3ef5778527cf98eae0433e9d1f18c929dd5d",
        "s": "0x08c75921e6bb75e19112300f80998f88a2b0f1adc52df2c3597b171d8c8de68d",
        "yParity": "0x1",
        "v": "0x1",
        "hash": "0x6a010a5ce041ff0ee5a926db65d1ef512836cae822d5f2d58b63981bfa40aa7f",
        "blockHash": null,
        "blockNumber": "0x2c679a1",
        "transactionIndex": "0x83",
        "from": "0x2ad149d3d3099532d7c25c47cce37db6c4677b3a",
        "gasPrice": "0x8de7bc",
        "gasUsed": "0x26132",
        "status": "0x1",
        "cumulativeGasUsed": "0x16cb406",
        "contractAddress": null,
        "logsBloom": "0x00...00",
        "logs": []
      }
    }
  }
  ```
</CodeGroup>