> For the complete documentation index, see [llms.txt](https://docs.getblock.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.getblock.io/api-reference/nervos-ckb/sync_state-nervos.md).

# sync\_state - Nervos

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

{% tabs %}
{% tab title="cURL" %}

```bash
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"
}'
```

{% endtab %}

{% tab title="JavaScript (Axios)" %}

```javascript
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));
```

{% endtab %}

{% tab title="Python (Requests)" %}

```python
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)
```

{% endtab %}

{% tab title="Rust (Reqwest)" %}

```rust
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(())
}
```

{% endtab %}
{% endtabs %}

## Response Example

{% code overflow="wrap" %}

```json
{
    "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"
    }
}
```

{% endcode %}

## 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

{% tabs %}
{% tab title="@ckb-lumos/lumos" %}

```javascript
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);
```

{% endtab %}

{% tab title="ckb-sdk-python / requests" %}

```python
# 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())
```

{% endtab %}
{% endtabs %}


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.getblock.io/api-reference/nervos-ckb/sync_state-nervos.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.