Flashblocks API

Flashblocks API on the Base network: fetch the latest in-progress block, including all preconfirmed transactions. Quickstart examples in JavaScript and Python

This section contains all the Flashblock methods available on the Base network

To make use of Flashblocks:

Flashblocks are simply a class of RPC API methods that are now active on GetBlock endpoints for Base and Optimism. If you already run either chain with GetBlock, the new methods are available on your existing endpoint; if you are new, set up a Base or Optimism endpoint from the GetBlock dashboard and the methods are there.

Quickstart

In this section, you will learn how to fetch the latest Flashblock — the current in-progress block containing every preconfirmed transaction — using either:

• Axios (JavaScript / Node.js)

• Python (Requests library)

Before you begin, you must have already installed npm or yarn on your local machine (for the Axios example) or Python and pip (for the Python example).

JavaScript (Axios)

1

Setup project

mkdir flashblocks-quickstart
cd flashblocks-quickstart
npm init --yes

2

Install Axios

npm install axios

3

Create file

Create a new file named index.js. This is where you will make your first call.

4

Set ES module type

Set the ES module "type": "module" in your package.json.

5

Add code

index.js

import axios from 'axios';

// Fetch the latest Flashblock (in-progress block with preconfirmed transactions)
const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "eth_getBlockByNumber",
    "params": ["pending", false],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers: {
        'Content-Type': 'application/json'
    },
    data: data
};

axios(config)
    .then(response => console.log(JSON.stringify(response.data, null, 2)))
    .catch(error => console.log(error));

Replace <ACCESS-TOKEN> with your actual access token from GetBlock (Base or Optimism endpoint).

6

Run the script

node index.js

The response contains the current in-progress block, updated every 200ms (Base) or 250ms (Optimism). Call it again a few hundred milliseconds later and you'll see additional transactions included as new Flashblocks land.

7

Result

{
    "jsonrpc": "2.0",
    "result": {
        "hash": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "parentHash": "0x64c3e43c9701407d6fb8bd853782a7fc77ba7f63e55a1cd1c5eaa1c0eaf3e8c4",
        "sha3Uncles": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
        "miner": "0x4200000000000000000000000000000000000011",
        "stateRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "transactionsRoot": "0x38131951ed5e3c8fa20b3cb08a75ccc33cb19e3a3cdf6260eae76a173900b934",
        "receiptsRoot": "0x83434863672598b03e64b1effdb3ad205345ad5114fd8b55995ad26571663a40",
        "logsBloom": "0x363031c23351743880d55105b76437b4e05246402bc44898a3353f4531021a41092f44aab543e301cf9f41d3a1a636817fd88880854d2114e7260fc360b46ef01f7a875144df34dc8f308f08ab498b24167c560d99ff32b5b0d3676a87638c373f9ea87cbe7a0b186609584f972b2ca8b1608b028894556464c28195591b539094351a2d3b3979be4623f816c522b87e372b826b2aa47a4cf27f20759540d4990e742b86a08811cf5e40b7370dcec2807bc44273421c8e5afff70b23407a5cd2be20996a72898ce94611dcd1ab2590a5080d878a8e78f83af193c6c3f908ec64621ebd8c179c90a3b4420f2c0aeb5cb6f0ba86c2b59e2956b2343d70af419883",
        "difficulty": "0x0",
        "number": "0x2de03b4",
        "gasLimit": "0x17d78400",
        "gasUsed": "0x11b1f57",
        "timestamp": "0x6a46644b",
        "extraData": "0x01000000640000000500000000004c4b40",
        "mixHash": "0xcb2806e22a6932ee882e44cb4899082c4eb130745740b14f5110d32c0e463236",
        "nonce": "0x0000000000000000",
        "baseFeePerGas": "0x4c4b40",
        "withdrawalsRoot": "0x5a6218671840987892338b76625664c7060d7b55b9e82414f9117f5388c406d4",
        "blobGasUsed": "0x351e14",
        "excessBlobGas": "0x0",
        "parentBeaconBlockRoot": "0x41922b97f16dd4c26d9680c0888d6eca48a96638988a310578c91cb1f76865ea",
        "requestsHash": "0xe3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
        "uncles": [],
        "transactions": [
            "0x736d0f7b161888aef73271d4d147fa4ba5a4a42b1ef018fdab3605091aee21e3"      "0xe58be418f85a1281a3c0ba4951c33edf948568879acda466663d568512ec8e92",        "0x5bf2fba339a689973db07c54e1c22556c07a0c7fdcdf3f4918b2b7bd6fee75ab"     "0xa6bec80fa9c94c0d330e27421e414eaef85cc39800120a557b3e93dcb9e81adb",
            "0x7f291369918ece59ccc88efde10a9807aa7da285dfec7744d5cc184b75227ba8"
        ],
        "withdrawals": []
    },
    "id": 1
}

Python (Requests)