simulate

The simulate method executes a dry run of any transaction type, enabling you to preview the results and metadata of a transaction without committing them to the XRP Ledger. Since this command never submits a transaction to the network, it doesn't incur any fees.

Caution

The simulate method isn't guaranteed to be the same when you actually submit a transaction because the ledger state--which affects how a transaction is processed--can change between the transaction simulation and submission.

Request Format

curl --location 'https://xrp.nownodes.io' \
--header 'api-key: API_KEY' \
--header 'Content-Type: application/json' \
--data '{
    "method": "simulate",
    "params": {
        "tx_json" : {
            "TransactionType" : "Payment",
            "Account" : "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
            "Destination" : "ra5nK24KXen9AHvsdFTKHSANinZseWnPcX",
            "Amount" : {
                "currency" : "USD",
                "value" : "1",
                "issuer" : "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn"
            }
        }
    }
}'

The request includes the following parameters:

Field	Type	Required?	Description
tx_blob	String	Yes	The transaction to simulate, in binary format. If you include this field, do not also include tx_json.
tx_json	Object	Yes	The transaction to simulate, in JSON format. If you include this field, do not also include tx_blob.
binary	Boolean	No	The default value is false, which returns data and metadata in JSON format. If true, returns data and metadata in binary format, serialized to a hexadecimal string.

• The simulated transaction must be unsigned.

• The server autofills Fee, Sequence, SigningPubKey, and NetworkID fields.

Response Format

An example of a successful response:

{
  "id": 2,
  "result": {
    "applied": false,
    "engine_result": "tesSUCCESS",
    "engine_result_code": 0,
    "engine_result_message": "The simulated transaction would have been applied.",
    "ledger_index": 3,
    "meta": {
      "AffectedNodes": [
        {
          "ModifiedNode": {
            "FinalFields": {
              "Account": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
              "AccountTxnID": "4D5D90890F8D49519E4151938601EF3D0B30B16CD6A519D9C99102C9FA77F7E0",
              "Balance": "75159663",
              "Flags": 9043968,
              "OwnerCount": 5,
              "Sequence": 361,
              "TransferRate": 1004999999
            },
            "LedgerEntryType": "AccountRoot",
            "LedgerIndex": "13F1A95D7AAB7108D5CE7EEAF504B2894B8C674E6D68499076441C4837282BF8",
            "PreviousFields": {
              "AccountTxnID": "2B44EBE00728D04658E597A85EC4F71D20503B31ABBF556764AD8F7A80BA72F6",
              "Balance": "75169663",
              "Sequence": 360
            },
            "PreviousTxnID": "2B44EBE00728D04658E597A85EC4F71D20503B31ABBF556764AD8F7A80BA72F6",
            "PreviousTxnLgrSeq": 18555460
          }
        },
        {
          "ModifiedNode": {
            "FinalFields": {
              "Balance": {
                "currency": "USD",
                "issuer": "rrrrrrrrrrrrrrrrrrrrBZbvji",
                "value": "12.0301"
              },
              "Flags": 65536,
              "HighLimit": {
                "currency": "USD",
                "issuer": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
                "value": "0"
              },
              "HighNode": "0",
              "LowLimit": {
                "currency": "USD",
                "issuer": "ra5nK24KXen9AHvsdFTKHSANinZseWnPcX",
                "value": "100"
              },
              "LowNode": "0"
            },
            "LedgerEntryType": "RippleState",
            "LedgerIndex": "96D2F43BA7AE7193EC59E5E7DDB26A9D786AB1F7C580E030E7D2FF5233DA01E9",
            "PreviousFields": {
              "Balance": {
                "currency": "USD",
                "issuer": "rrrrrrrrrrrrrrrrrrrrBZbvji",
                "value": "11.0301"
              }
            },
            "PreviousTxnID": "7FFE02667225DFE39594663DEDC823FAF188AC5F036A9C2CA3259FB5379C82B4",
            "PreviousTxnLgrSeq": 9787698
          }
        }
      ],
      "TransactionIndex": 0,
      "TransactionResult": "tesSUCCESS",
      "delivered_amount": {
        "currency": "USD",
        "issuer": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
        "value": "1"
      }
    },
    "tx_json": {
      "Account": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
      "DeliverMax": {
        "currency": "USD",
        "issuer": "rf1BiGeXwwQoi8Z2ueFYTEXSwuJYfV2Jpn",
        "value": "1"
      },
      "Destination": "ra5nK24KXen9AHvsdFTKHSANinZseWnPcX",
      "Fee": "10",
      "Sequence": 360,
      "TransactionType": "Payment"
    }
  },
  "status": "success",
  "type": "response"
}

The response follows the standard format, with a successful result containing the following fields:

Field	Type	Description
tx_json	Object	The transaction that was simulated, including auto-filled values. Included if binary was false.
tx_blob	String	The serialized transaction that was simulated, including auto-filled values. Included if binary was true.
ledger_index	Ledger Index	The ledger index of the ledger that would have included this transaction.
meta	Object	Transaction metadata, which describes the results of the transaction. Not included if the transaction fails with a code that means it wouldn’t be included in the ledger (such as a non-TEC code). Included if binary was false.
meta_blob	String	Transaction metadata, which describes the results of the transaction. Not included if the transaction fails with a code that means it wouldn’t be included in the ledger (such as a non-TEC code). Included if binary was true.

Possible Errors

• invalidParams - One or more fields are specified incorrectly, or one or more required fields are missing.

• transactionSigned - The transaction was signed. The simulated transaction must be unsigned.