getBlocksWithLimit

Learn getBlocksWithLimit use cases, code examples, request parameters, response structure, and tips.

The getBlocksWithLimit RPC method retrieves a list of confirmed block slot numbers, starting from a specified slot and returning up to a defined limit. It’s especially useful when you need a fixed number of confirmed blocks following a known slot, without fetching full block data.

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✅ Common Use Cases

• Fetch a Fixed Number of Blocks Retrieve a specific number of confirmed block slots beginning at a particular start slot.

• Paginated Block Scanning Process the blockchain in manageable chunks—ideal for block explorers or analytics pipelines.

• Recent Block Monitoring Quickly get the most recent confirmed blocks following a known anchor slot.

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🛠 Request Parameters

getBlocksWithLimit accepts the following arguments:

• start_slot (u64, required): The first slot to start the query (inclusive).

• limit (u64, required): The maximum number of block slots to return. ⚠️ The conceptual slot range (start_slot to start_slot + limit - 1) must not exceed 500,000 slots.

• commitment (string, optional): Commitment level for block confirmation:

  • finalized (default)

  • confirmed

  • processed If provided, this must be wrapped in a configuration object as the last parameter.

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📦 Response Structure

The result field contains an array of confirmed block slot numbers, up to the requested limit.

Example:

[355104000, 355104001, 355104002, 355104003, 355104004]

If start_slot is 355104000and limit is 5, this array represents the confirmed blocks found in that range.

💡 Examples

1. Fetch 5 Confirmed Blocks from a Start Slot

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "getBlocksWithLimit",
  "params": [355104000, 5]
}

1. Fetch 3 Confirmed Blocks with a Specific Commitment Level

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "getBlocksWithLimit",
  "params": [355104000, 3, { "commitment": "confirmed" }]
}

Code Examples

Nodejs

const fetch = require('node-fetch');

async function getBlocksWithLimit(rpcUrl) {
  try {
    const response = await fetch(rpcUrl, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        jsonrpc: '2.0',
        id: 1,
        method: 'getBlocksWithLimit',
        "params": [
            355104000,
            5,
            { "commitment": "confirmed" }
          ]
      }),
    });

    const data = await response.json();
    
    // Print the exact full response
    console.log('Full RPC Response:');
    console.log(JSON.stringify(data, null, 2));
    
    return data;
  } catch (error) {
    console.error('Error getting health:', error.message);
    return null;
  }
}

// Example usage
const RPC_URL = 'https://rpc.coinvera.io/?x-api-key=your-coinvera-x-api-key';

getBlocksWithLimit(RPC_URL);

Python

import json
import asyncio
import aiohttp

async def get_blocks_with_limit(rpc_url):
    try:
        payload = {
            "jsonrpc": "2.0",
            "id": 1,
            "method": "getBlocksWithLimit",
            "params": [
                355104000,
                5,
                {"commitment": "confirmed"}
            ]
        }
        
        async with aiohttp.ClientSession() as session:
            async with session.post(
                rpc_url,
                headers={'Content-Type': 'application/json'},
                json=payload
            ) as response:
                data = await response.json()
                
                # Print the exact full response
                print('Full RPC Response:')
                print(json.dumps(data, indent=2))
                
                return data
                
    except Exception as error:
        print(f'Error getting health: {error}')
        return None

# Example usage
async def main():
    RPC_URL = 'https://rpc.coinvera.io/?x-api-key=your-coinvera-x-api-key'
    await get_blocks_with_limit(RPC_URL)

# Run the async function
if __name__ == "__main__":
    asyncio.run(main())

Example Respose

{
  "jsonrpc": "2.0",
  "result": [
    355104000,
    355104001,
    355104002,
    355104003,
    355104004
  ],
  "id": 1
}

🧠 Developer Tips

• Understand Range Constraints The conceptual range scanned is from start_slot to start_slot + limit - 1. This must be ≤ 500,000 slots, regardless of how many actual blocks are returned.

• Ledger Retention Limits RPC nodes (like CoinVera) may not retain block info for very old slots. If start_slot is too far in the past, the method might return fewer blocks than expected—or none at all.

• Block Confirmation Levels The blocks returned reflect those confirmed at the specified commitment level. Recently confirmed blocks may vary slightly across nodes and configurations.

• Choosing the Right Method Use getBlocksWithLimit when you:

  • Know where to start

  • Want a fixed number of results For scanning a known range, use getBlocks instead.