construction/submit - Cardano

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

This endpoint broadcasts a signed transaction to the network and returns its transaction hash on acceptance. It is the final, online step of the construction flow.

Parameters

The request body is a JSON object with the following fields.

Field	Type	Required	Description
network_identifier	object	Yes	The network to submit to
signed_transaction	string	Yes	The signed transaction CBOR hex

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/construction/submit' \
--header 'Content-Type: application/json' \
--data-raw '{
    "network_identifier": {
        "blockchain": "cardano",
        "network": "mainnet"
    },
    "signed_transaction": "84a400818258200e...signed-cbor..."
}'

JavaScript

example.js

const response = await fetch(
    'https://go.getblock.io/<ACCESS-TOKEN>/construction/submit',
    {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({"network_identifier": {"blockchain": "cardano", "network": "mainnet"}, "signed_transaction": "84a400818258200e...signed-cbor..."})
    }
);
console.log(await response.json());

Python

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/construction/submit',
    headers={'Content-Type': 'application/json'},
    json={"network_identifier": {"blockchain": "cardano", "network": "mainnet"}, "signed_transaction": "84a400818258200e...signed-cbor..."}
)

print(response.json())

Response

{
    "transaction_identifier": {
        "hash": "10b54fd708ab2e5703979b4ba27ca0339882abc2062e77fbe51e625203a49642"
    }
}

Response Parameters

Field	Type	Description
transaction_identifier	object	The hash of the accepted transaction

Use Cases

• Payment Broadcast: Submit a signed transaction to the network

• dApp Backends: Broadcast transactions built through the construction flow

• Exchange Withdrawals: Submit signed withdrawal transactions

• Retry Flows: Resubmit a signed transaction from stored CBOR

Error Handling

Error Code	Message	Description
1	Invalid request	The signed transaction is missing or malformed
6	Transaction decode failed	The signed transaction could not be decoded
9	Transaction rejected	The node rejected the transaction during submission
5	Internal error	The node failed to broadcast the transaction