eth_call - Flashblocks

Example code for the eth_call - Flashblocks method. Complete guide on how to use eth_call - Flashblocks in GetBlock Web3 documentation.

This executes a read-only contract call without creating a transaction. When the block reference is "pending", the call executes against state including every transaction preconfirmed into the latest Flashblocks. This lets applications compute derived values (token balances, oracle prices, pool reserves) reflecting the freshest possible state.

Parameters

Parameter	Type	Required	Description
callObject	object	Yes	Call params: to, data, from (optional), gas (optional), gasPrice (optional), value (optional)
block	QUANTITY	TAG	Yes

Request Example

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "eth_call",
    "params": [
        {
            "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
            "data": "0x70a082310000000000000000000000007a25d0f0ff6a25f36de0a19c3d5f6dc2c6eaed6a"
        },
        "pending"
    ],
    "id": "getblock.io"
}'

JavaScript (Axios)

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "eth_call",
    "params": [
        {
            "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
            "data": "0x70a082310000000000000000000000007a25d0f0ff6a25f36de0a19c3d5f6dc2c6eaed6a"
        },
        "pending"
    ],
    "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));

Python (Requests)

import requests
import json

url = "https://go.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "eth_call",
    "params": [
        {
            "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
            "data": "0x70a082310000000000000000000000007a25d0f0ff6a25f36de0a19c3d5f6dc2c6eaed6a"
        },
        "pending"
    ],
    "id": "getblock.io"
})

headers = {
    'Content-Type': 'application/json'
}

response = requests.post(url, headers=headers, data=payload)
print(response.text)

Rust (Reqwest)

use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::new();

    let payload = json!({
        "jsonrpc": "2.0",
        "method": "eth_call",
        "params": [
                {
                        "to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
                        "data": "0x70a082310000000000000000000000007a25d0f0ff6a25f36de0a19c3d5f6dc2c6eaed6a"
                },
                "pending"
        ],
        "id": "getblock.io"
});

    let response = client
        .post("https://go.getblock.io/<ACCESS-TOKEN>/")
        .header("Content-Type", "application/json")
        .json(&payload)
        .send()
        .await?;

    let result: serde_json::Value = response.json().await?;
    println!("{:#?}", result);

    Ok(())
}

Response Example

{
    "jsonrpc": "2.0",
    "id": "getblock.io",
    "result": "0x000000000000000000000000000000000000000000000000000000000098967f"
}

Response Parameters

Field	Type	Description
result	DATA	ABI-encoded return value from the contract call

Use Cases

• Reading ERC-20 balances / allowances reflecting the latest preconfirmed transfers

• Fetching oracle prices with sub-block latency

• Pre-flight quotes for DEX swaps against the freshest reserves

• Any read that needs to reflect state 200ms ahead of the standard latest tag

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid <ACCESS-TOKEN>
-32602	Invalid params	Request parameters are missing or malformed
-32603	Internal error	Server-side error while processing the request
429	Too Many Requests	Rate limit exceeded for your plan
3	execution reverted	Contract execution reverted — the contract's logic rejected the call
-32602	Invalid call object	Malformed call parameters

SDK Integration

ethers.js

import { ethers } from 'ethers';

const provider = new ethers.JsonRpcProvider('https://go.getblock.io/<ACCESS-TOKEN>/');

// Generic JSON-RPC call — 'pending' returns Flashblocks-preconfirmed state:
const result = await provider.send('eth_call', [{"to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "data": "0x70a082310000000000000000000000007a25d0f0ff6a25f36de0a19c3d5f6dc2c6eaed6a"}, "pending"]);
console.log(result);

// Many standard methods have typed wrappers on ethers Provider that accept 'pending':
// provider.getBalance(addr, 'pending'), provider.getTransactionCount(addr, 'pending'), etc.

viem

import { createPublicClient, http } from 'viem';

const client = createPublicClient({
    transport: http('https://go.getblock.io/<ACCESS-TOKEN>/')
});

// viem's read methods accept blockTag: 'pending' for Flashblocks-preconfirmed state:
const result = await client.request({
    method: 'eth_call',
    params: [{"to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913", "data": "0x70a082310000000000000000000000007a25d0f0ff6a25f36de0a19c3d5f6dc2c6eaed6a"}, "pending"]
});
console.log(result);

// Typed wrappers also accept blockTag: 'pending':
// client.getBalance({ address, blockTag: 'pending' })
// client.getBlock({ blockTag: 'pending' })