Simulate transaction

POST

https://soroban-testnet.nownodes.io/rpc

Authorizations

ApiKeyAuthApiKeyAuth

api-key string

NOWNodes API key passed in the api-key header.

Submit a trial contract invocation to simulate how it would be executed by the network. This endpoint calculates the effective transaction data, required authorizations, and minimal resource fee. It provides a way to test and analyze the potential outcomes of a transaction without actually submitting it to the network.

Body

application/json

jsonrpcstringrequired

idintegerrequired

methodstringrequired

paramsobjectrequired

Show child attributes

transactionstringrequired

resourceConfigobject

Show child attributes

instructionLeewayinteger

Response

200OK

Transaction simulation completed successfully

400Bad Request

Bad Request

401Unauthorized

Unauthorized — Missing or invalid API key

500Internal Server Error

Internal Server Error

Simulate transaction

curl -X POST 'https://soroban-testnet.nownodes.io/rpc' \
  -H 'Content-Type: application/json' \
  -d '{
    "jsonrpc": "2.0",
    "id": 8675309,
    "method": "simulateTransaction",
    "params": {
      "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
      "resourceConfig": {
        "instructionLeeway": 3000000
      }
    }
  }'

import { JsonRpcProvider } from "ethers";

const provider = new JsonRpcProvider("https://soroban-testnet.nownodes.io/rpc");
const result = await provider.send("simulateTransaction", {
  "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
  "resourceConfig": {
    "instructionLeeway": 3000000
  }
});
console.log(result);

require 'eth'
require 'json'
require 'net/http'

uri = URI('https://soroban-testnet.nownodes.io/rpc')
request = Net::HTTP::Post.new(uri)
request['Content-Type'] = 'application/json'
request.body = '{
  "jsonrpc": "2.0",
  "method": "simulateTransaction",
  "params": {
    "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
    "resourceConfig": {
      "instructionLeeway": 3000000
    }
  },
  "id": 1
}'

response = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) do |http|
  http.request(request)
end

puts JSON.parse(response.body)

from web3 import Web3

w3 = Web3(Web3.HTTPProvider("https://soroban-testnet.nownodes.io/rpc"))
response = w3.provider.make_request("simulateTransaction", {
  "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
  "resourceConfig": {
    "instructionLeeway": 3000000
  }
})
print(response)

import { createPublicClient, http } from "viem";

const client = createPublicClient({
  transport: http("https://soroban-testnet.nownodes.io/rpc"),
});

const result = await client.request({
  method: "simulateTransaction",
  params: {
  "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
  "resourceConfig": {
    "instructionLeeway": 3000000
  }
},
});

console.log(result);

const endpoint = "https://soroban-testnet.nownodes.io/rpc";
const apiKey = "YOUR_API_KEY";

async function nownodesRequest(payload) {
  const response = await fetch(endpoint, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "api-key": apiKey,
    },
    body: JSON.stringify(payload),
  });

  return response.json();
}

const result = await nownodesRequest({ jsonrpc: "2.0", method: "simulateTransaction", params: {
  "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
  "resourceConfig": {
    "instructionLeeway": 3000000
  }
}, id: 1 });
console.log(result);

const response = await fetch('https://soroban-testnet.nownodes.io/rpc', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
      "jsonrpc": "2.0",
      "id": 8675309,
      "method": "simulateTransaction",
      "params": {
        "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
        "resourceConfig": {
          "instructionLeeway": 3000000
        }
      }
    }),
});

const data = await response.json();

import requests

payload = {
  "jsonrpc": "2.0",
  "id": 8675309,
  "method": "simulateTransaction",
  "params": {
    "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
    "resourceConfig": {
      "instructionLeeway": 3000000
    }
  }
}

response = requests.post('https://soroban-testnet.nownodes.io/rpc', json=payload)
data = response.json()

require 'net/http'
require 'json'

uri = URI('https://soroban-testnet.nownodes.io/rpc')
request = Net::HTTP::Post.new(uri)
request['Content-Type'] = 'application/json'
request.body = '{
    "jsonrpc": "2.0",
    "id": 8675309,
    "method": "simulateTransaction",
    "params": {
      "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
      "resourceConfig": {
        "instructionLeeway": 3000000
      }
    }
  }'

response = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |http| http.request(request) }
data = JSON.parse(response.body)

Request Body

{
  "jsonrpc": "2.0",
  "id": 8675309,
  "method": "simulateTransaction",
  "params": {
    "transaction": "AAAAAgAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAGQAJsOiAAAAEQAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAAAAAAAGAAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAJaW5jcmVtZW50AAAAAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAMAAAAAAAAAAAAAAAA=",
    "resourceConfig": {
      "instructionLeeway": 3000000
    }
  }
}

200

{
  "jsonrpc": "2.0",
  "id": 8675309,
  "result": {
    "transactionData": "AAAAAAAAAAIAAAAGAAAAAcwD/nT9D7Dc2LxRdab+2vEUF8B+XoN7mQW21oxPT8ALAAAAFAAAAAEAAAAHy8vNUZ8vyZ2ybPHW0XbSrRtP7gEWsJ6zDzcfY9P8z88AAAABAAAABgAAAAHMA/50/Q+w3Ni8UXWm/trxFBfAfl6De5kFttaMT0/ACwAAABAAAAABAAAAAgAAAA8AAAAHQ291bnRlcgAAAAASAAAAAAAAAAAg4dbAxsGAGICfBG3iT2cKGYQ6hK4sJWzZ6or1C5v6GAAAAAEAHfKyAAAFiAAAAIgAAAAAAAAAAw==",
    "minResourceFee": "90353",
    "events": [
      "AAAAAQAAAAAAAAAAAAAAAgAAAAAAAAADAAAADwAAAAdmbl9jYWxsAAAAAA0AAAAgzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAAPAAAACWluY3JlbWVudAAAAAAAABAAAAABAAAAAgAAABIAAAAAAAAAACDh1sDGwYAYgJ8EbeJPZwoZhDqEriwlbNnqivULm/oYAAAAAwAAAAM=",
      "AAAAAQAAAAAAAAABzAP+dP0PsNzYvFF1pv7a8RQXwH5eg3uZBbbWjE9PwAsAAAACAAAAAAAAAAIAAAAPAAAACWZuX3JldHVybgAAAAAAAA8AAAAJaW5jcmVtZW50AAAAAAAAAwAAAAw="
    ],
    "results": [
      {
        "auth": [
          "string"
        ],
        "xdr": "AAAAAwAAAAw="
      }
    ],
    "cost": {
      "cpuInsns": "1635562",
      "memBytes": "1295756"
    },
    "latestLedger": 2552139
  }
}

Documentation

How to migrate to NOWNodes

Simulate transaction

Authorizations

Body

Response