sync_state - Nervos

Example code for the sync_state JSON-RPC method. Complete guide on how to use sync_state JSON-RPC in GetBlock Web3 documentation.

Returns the chain synchronization state of this node — total best known header, currently fast-syncing block, in-flight blocks, current low time.

Parameters

• None

Request Example

cURL

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

JavaScript (Axios)

import axios from 'axios';

const data = JSON.stringify({
    "jsonrpc": "2.0",
    "method": "sync_state",
    "params": [],
    "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": "sync_state",
    "params": [],
    "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": "sync_state",
        "params": [],
        "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": {
        "best_known_block_number": "0xe5a45f",
        "best_known_block_timestamp": "0x18f3b8d2a3c",
        "fast_time": "0x1f4",
        "ibd": false,
        "inflight_blocks_count": "0x0",
        "low_time": "0x9c4",
        "normal_time": "0x3e8",
        "orphan_blocks_count": "0x0",
        "tip_hash": "0x02530b25ad0ff677acc365cb73de3e8cc09c7ddd58272e879252e199d08df83b",
        "tip_number": "0xe5a45f",
        "unverified_tip_hash": "0x02530b25ad0ff677acc365cb73de3e8cc09c7ddd58272e879252e199d08df83b",
        "unverified_tip_number": "0xe5a45f"
    }
}

Response Parameters

Field	Type	Description
result.ibd	boolean	true if the node is in Initial Block Download mode
result.best_known_block_number	Uint64	Highest block number known across all peers
result.tip_number	Uint64	Local tip block number
result.inflight_blocks_count	Uint64	Blocks currently being downloaded from peers
result.orphan_blocks_count	Uint64	Orphan blocks in local storage
result.normal_time	Uint64	Median time for block download (ms)
result.low_time	Uint64	p25 time for block download (ms)
result.fast_time	Uint64	p75 time for block download (ms)

Use Cases

• Detecting that a node is still in IBD before serving reads

• Monitoring sync progress in node dashboards

• Failover logic that prefers fully-synced nodes

Error Handling

Status Code	Error Message	Cause
403	Forbidden	Missing or invalid <ACCESS-TOKEN>
-32602	Invalid params	Request parameters are missing or malformed
-32601	Method not found	Method does not exist or is not enabled on this node
-32603	Internal error	Server-side error while processing the request
429	Too Many Requests	Rate limit exceeded for your plan

SDK Integration

@ckb-lumos/lumos

import { RPC } from '@ckb-lumos/rpc';

const rpc = new RPC('https://go.getblock.io/<ACCESS-TOKEN>/');

// Lumos provides typed methods on `rpc` (e.g. rpc.getTipHeader(), rpc.getBlock(hash)).
// For raw access to any CKB RPC method:
const result = await rpc.send('sync_state', []);
console.log(result);

ckb-sdk-python / requests

# Using the official CKB SDK Python (ckb-sdk-python).
# For methods not yet wrapped, fall back to raw requests.
import requests

response = requests.post('https://go.getblock.io/<ACCESS-TOKEN>/', json={
    'jsonrpc': '2.0',
    'id': 'getblock.io',
    'method': 'sync_state',
    'params': []
}})
print(response.json())