zks_getL2ToL1LogProof - zkSync

Example code for the zks_getL2ToL1LogProof JSON-RPC method. Сomplete guide on how to use zks_getL2ToL1LogProof JSON-RPC in GetBlock.io Web3 documentation.

Retrieves the log proof for an L2 to L1 transaction. The log proof can only be generated after the corresponding L2 transaction has been finalized (executed) on L1. Use this proof to claim withdrawals on L1.

Parameters

Parameter	Type	Required	Description
txHash	string	Yes	Transaction hash (32 bytes)
logIndex	integer	No	Index of the log (optional for EraVM chains)

Request Example

cURL

curl --location --request POST 'https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "zks_getL2ToL1LogProof",
    "params": [
        "0x2a1c6c74b184965c0cb015aae9ea134fd96215d2e4f4979cfec12563295f610e"
    ],
    "id": "getblock.io"
}'

JavaScript (Axios)

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "zks_getL2ToL1LogProof",
    "params": [
        "0x2a1c6c74b184965c0cb015aae9ea134fd96215d2e4f4979cfec12563295f610e"
    ],
    "id": "getblock.io"
});

const config = {
    method: 'post',
    url: 'https://shared.eu-central-1.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://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/"

payload = json.dumps({
    "jsonrpc": "2.0",
    "method": "zks_getL2ToL1LogProof",
    "params": [
        "0x2a1c6c74b184965c0cb015aae9ea134fd96215d2e4f4979cfec12563295f610e"
    ],
    "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": "zks_getL2ToL1LogProof",
        "params": [
                "0x2a1c6c74b184965c0cb015aae9ea134fd96215d2e4f4979cfec12563295f610e"
        ],
        "id": "getblock.io"
});

    let response = client
        .post("https://shared.eu-central-1.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": {
        "proof": [
            "0x8c48910df2ca7de509daf50b3182fcdf2dd6c422c6704054fd857d6c9516d6fc",
            "0xc5028885760b8b596c4fa11497c783752cb3a3fb3b8e6b52d7e54b9f1c63521e"
        ],
        "id": 0,
        "root": "0x920c63cb0066a08da45f0a9bf934517141bd72d8e5a51421a94b517bf49a0d39",
        "batchNumber": 21710
    }
}

Response Parameters

Field	Type	Description
result.proof	array of string	Array of 32-byte hashes — the Merkle proof for the log
result.id	integer	Identifier of the log within the transaction
result.root	string	Root hash anchoring the proof
result.batchNumber	integer	L1 batch number where the log was executed

Use Cases

• L2 → L1 withdrawals — required to finalize on L1

• Cross-chain messaging proofs

• Trust-minimized L2 → L1 message verification

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid <ACCESS-TOKEN>
429	Too Many Requests	Rate limit exceeded for your plan

SDK Integration

zksync-ethers (JavaScript)

import { Provider } from 'zksync-ethers';

const provider = new Provider('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/');

// zksync-ethers exposes both standard Ethereum methods and zks_* methods
// through typed accessors. For raw access:
const result = await provider.send('zks_getL2ToL1LogProof', ["0x2a1c6c74b184965c0cb015aae9ea134fd96215d2e4f4979cfec12563295f610e"]);
console.log(result);

zksync2-python (Python)

from zksync2.module.module_builder import ZkSyncBuilder

zk_web3 = ZkSyncBuilder.build('https://shared.eu-central-1.getblock.io/<ACCESS-TOKEN>/')

# zksync2-python exposes the JSON-RPC layer directly.
result = zk_web3.zksync._zks_endpoints if 'zks_getL2ToL1LogProof'.startswith('zks_') else None
# Or call any method generically:
result = zk_web3.provider.make_request('zks_getL2ToL1LogProof', ["0x2a1c6c74b184965c0cb015aae9ea134fd96215d2e4f4979cfec12563295f610e"])
print(result)