evaluateTransaction - Cardano

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

This method evaluates the execution units required by the Plutus scripts in a transaction, without submitting it. It returns the memory and CPU budget each script requires.

Parameters

Parameter	Type	Required	Description
transaction	object	Yes	Object with a cbor field holding the base16 transaction
additionalUtxo	array	No	Extra UTXOs to resolve inputs not yet on-chain

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/' \
--header 'Content-Type: application/json' \
--data-raw '{
    "jsonrpc": "2.0",
    "method": "evaluateTransaction",
    "params": {
        "transaction": {
            "cbor": "84a300818258200e...transaction-cbor-hex...ff"
        },
        "additionalUtxo": []
    },
    "id": "getblock.io"
}'

JavaScript

example.js

const response = await fetch(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({"jsonrpc": "2.0", "method": "evaluateTransaction", "params": {"transaction": {"cbor": "84a300818258200e...transaction-cbor-hex...ff"}, "additionalUtxo": []}, "id": "getblock.io"})
    }
);
console.log(await response.json());

Python

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/',
    headers={'Content-Type': 'application/json'},
    json={"jsonrpc": "2.0", "method": "evaluateTransaction", "params": {"transaction": {"cbor": "84a300818258200e...transaction-cbor-hex...ff"}, "additionalUtxo": []}, "id": "getblock.io"}
)

print(response.json())

Response

{
    "jsonrpc": "2.0",
    "method": "evaluateTransaction",
    "result": [
        {
            "validator": {
                "index": 0,
                "purpose": "spend"
            },
            "budget": {
                "memory": 1700000,
                "cpu": 476468950
            }
        }
    ],
    "id": "getblock.io"
}

Response Parameters

Field	Type	Description
validator	object	The redeemer's index and purpose
budget	object	Required memory and CPU execution units

Use Cases

• Script Budgeting: Measure execution units before submitting

• Fee Estimation: Price script execution into the transaction fee

• dApp Testing: Validate that scripts stay within limits

• Transaction Building: Set redeemer budgets from measured units

Error Handling

Error Code	Message	Description
-32602	Invalid params	The transaction CBOR is missing or malformed
3010	Cannot create evaluation context	The additional UTXO set could not be resolved
3011	Script execution failure	One or more scripts failed during evaluation
-32603	Internal error	The node failed to evaluate the transaction