author_submitExtrinsic - JSON-RPC Method

Description

Submits a fully formatted and signed extrinsic (transaction) to the Polkadot network's transaction pool for inclusion in a block. This method is essential for broadcasting transactions to the network.

Parameters

Parameter	Type	Required	Description
extrinsic	string	Yes	Hex-encoded signed extrinsic to submit to the network

Returns

Field	Type	Description
result	string	Transaction hash of the submitted extrinsic

Request Example

{
  "jsonrpc": "2.0",
  "method": "author_submitExtrinsic",
  "params": [
    "0x450284008eaf04151687736326c9fea17e25fc5287613693c912909cb226aa4794f26a480284d717d5031504025a62020b00000000000000e143f23803ac50e8f6f8e62695d1ce9e4e1d68aa36c1cd2cfd15340213f3423e3aedc952073c01f1c4d76ccd8c18d0f900fcb6ac003a5f08709e3c9038b68055"
  ],
  "id": 1
}

Response Example

{
  "jsonrpc": "2.0",
  "result": "0x7c8b4d5a6f2e3c9d8a7b5e4f3c2d1a9b8c7e6f5d4c3b2a1",
  "id": 1
}

Code Examples

cURL

curl https://api-polkadot.n.dwellir.com \
  -X POST \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "author_submitExtrinsic",
    "params": ["0x450284..."],
    "id": 1
  }'

JavaScript (fetch)

const submitExtrinsic = async (signedExtrinsic) => {
  const response = await fetch('https://api-polkadot.n.dwellir.com', {
    method: 'POST',
    headers: {
      'Authorization': 'Bearer YOUR_API_KEY',
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      jsonrpc: '2.0',
      method: 'author_submitExtrinsic',
      params: [signedExtrinsic],
      id: 1
    })
  });
  
  const data = await response.json();
  return data.result; // Transaction hash
};

// Example usage
const txHash = await submitExtrinsic('0x450284...');
console.log('Transaction submitted:', txHash);

Python (requests)

import requests
import json

def submit_extrinsic(signed_extrinsic):
    url = "https://api-polkadot.n.dwellir.com"
    headers = {
        "Authorization": "Bearer YOUR_API_KEY",
        "Content-Type": "application/json"
    }
    
    payload = {
        "jsonrpc": "2.0",
        "method": "author_submitExtrinsic",
        "params": [signed_extrinsic],
        "id": 1
    }
    
    response = requests.post(url, headers=headers, data=json.dumps(payload))
    data = response.json()
    
    if "error" in data:
        raise Exception(f"RPC Error: {data['error']}")
    
    return data["result"]

# Example usage
tx_hash = submit_extrinsic("0x450284...")
print(f"Transaction submitted: {tx_hash}")

TypeScript (@polkadot/api)

import { ApiPromise, WsProvider } from '@polkadot/api';
import { Keyring } from '@polkadot/keyring';

async function submitTransaction() {
  // Connect to node
  const provider = new WsProvider('wss://api-polkadot.n.dwellir.com');
  const api = await ApiPromise.create({ provider });
  
  // Create keyring and add account
  const keyring = new Keyring({ type: 'sr25519' });
  const alice = keyring.addFromUri('//Alice');
  
  // Create and sign transaction
  const transfer = api.tx.balances.transfer(
    'RECIPIENT_ADDRESS',
    1000000000000 // 1 DOT (10^12 planck)
  );
  
  // Sign and submit
  const hash = await transfer.signAndSend(alice);
  console.log('Transaction hash:', hash.toHex());
  
  // Alternatively, submit pre-signed extrinsic
  const signedExtrinsic = transfer.sign(alice);
  const txHash = await api.rpc.author.submitExtrinsic(signedExtrinsic);
  console.log('Submitted via RPC:', txHash.toHex());
}

Use Cases

1. Token Transfers: Submit balance transfer transactions
2. Staking Operations: Delegate, bond, or unbond DOT tokens
3. Governance: Submit votes, proposals, or referenda
4. Smart Contract Calls: Execute contract methods
5. Parachain Operations: Cross-chain message passing

Error Handling

Common Errors

Error Code	Description	Solution
-32602	Invalid extrinsic format	Ensure extrinsic is properly hex-encoded
-32603	Invalid signature	Verify the extrinsic is correctly signed
1010	Invalid transaction	Check nonce, mortality period, and account balance
1012	Transaction pool full	Retry with higher priority fee
1013	Already in pool	Transaction already submitted

Error Response Example

{
  "jsonrpc": "2.0",
  "error": {
    "code": 1010,
    "message": "Invalid Transaction",
    "data": "Inability to pay some fees (e.g. account balance too low)"
  },
  "id": 1
}

Best Practices

1. Nonce Management: Always use the correct nonce to avoid transaction rejection
2. Fee Estimation: Calculate fees before submission using payment_queryFeeDetails
3. Mortality Period: Set appropriate mortality period for time-sensitive transactions
4. Error Handling: Implement robust error handling for network issues
5. Transaction Monitoring: Track transaction status after submission

Related Methods

• chain_getBlock - Verify transaction inclusion
• state_getMetadata - Get metadata for encoding
• system_health - Check node status before submission

Notes

• Extrinsics must be properly formatted and signed before submission
• The transaction hash returned is not a guarantee of inclusion in a block
• Monitor transaction status using subscription methods for critical operations
• Different transaction types require different encoding based on runtime metadata