# simulateTransaction

Simulate sending a transaction.

#### Parameters required for this RPC call

* Transaction, as an encoded string.
* The amount of lamports to airdrop
* **configuration object**: This contains the following parameters. All optional.
  * **encoding**: Encoding used for the transaction data. Values: `base58` (*slow*, **DEPRECATED**), or `base64`.
  * **commitment**: Commitment level to simulate the transaction at. See [Configuring State Commitment](https://solana.com/docs/rpc/index.mdx#configuring-state-commitment). Default `finalized`.
  * **replaceRecentBlockhash**: If `true` the transaction recent blockhash will be replaced with the most recent blockhash (conflicts with `sigVerify`)
  * **sigVerify**: If `true` the transaction signatures will be verified (conflicts with `replaceRecentBlockhash`)
  * **innerInstructions**: If `true` the response will include [inner instructions](https://solana.com/docs/rpc/json-structures#inner-instructions). These inner instructions will be `jsonParsed` where possible, otherwise `json`.
  * **accounts**: If `true` the response will include [inner instructions](https://solana.com/docs/rpc/json-structures#inner-instructions). These inner instructions will be `jsonParsed` where possible, otherwise `json`.
  * **minContextSlot**: Set the minimum slot at which to perform preflight transaction checks.

{% tabs %}
{% tab title="cURL" %}

<pre class="language-bash"><code class="lang-bash">curl https://rpc.shyft.to?api_key=YOUR-API-KEY -s -X \
<strong>  POST -H "Content-Type: application/json" -d ' 
</strong>   {
     "jsonrpc": "2.0",
     "id": 1,
     "method": "simulateTransaction",
     "params": [
       "AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAEEjNmKiZGiOtSZ+g0//wH5kEQo3+UzictY+KlLV8hjXcs44M/Xnr+1SlZsqS6cFMQc46yj9PIsxqkycxJmXT+veJjIvefX4nhY9rY+B5qreeqTHu4mG6Xtxr5udn4MN8PnBt324e51j94YQl285GzN2rYa/E2DuQ0n/r35KNihi/zamQ6EeyeeVDvPVgUO2W3Lgt9hT+CfyqHvIa11egFPCgEDAwIBAAkDZAAAAAAAAAA=",
       {
         "commitment": "confirmed",
         "encoding": "base64",
         "replaceRecentBlockhash": true
       }
     ]
   }
 '
</code></pre>

{% endtab %}

{% tab title="Web3.js" %}

```javascript
import {
  Connection,
  VersionedTransaction,
  clusterApiUrl,
  type SimulateTransactionConfig,
} from "@solana/web3.js";

const connection = new Connection("https://rpc.shyft.to?api_key=YOUR-API-KEY", "confirmed");

const base64Tx =
  "AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAEEjNmKiZGiOtSZ+g0//wH5kEQo3+UzictY+KlLV8hjXcs44M/Xnr+1SlZsqS6cFMQc46yj9PIsxqkycxJmXT+veJjIvefX4nhY9rY+B5qreeqTHu4mG6Xtxr5udn4MN8PnBt324e51j94YQl285GzN2rYa/E2DuQ0n/r35KNihi/zamQ6EeyeeVDvPVgUO2W3Lgt9hT+CfyqHvIa11egFPCgEDAwIBAAkDZAAAAAAAAAA=";

let tx = VersionedTransaction.deserialize(Buffer.from(base64Tx, "base64"));

let simulateTxConfig: SimulateTransactionConfig = {
  commitment: "finalized",
  replaceRecentBlockhash: true,
  sigVerify: false,
  minContextSlot: undefined,
  innerInstructions: undefined,
  accounts: undefined,
};

let simulateResult = await connection.simulateTransaction(tx, simulateTxConfig);

console.log(simulateResult);
```

{% endtab %}

{% tab title="Response" %}

```json
{
  "jsonrpc": "2.0",
  "result": {
    "context": {
      "apiVersion": "2.3.3",
      "slot": 393226680
    },
    "value": {
      "accounts": null,
      "err": null,
      "innerInstructions": null,
      "loadedAccountsDataSize": 413,
      "logs": [
        "Program TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb invoke [1]",
        "Program log: Instruction: Transfer",
        "Program TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb consumed 1714 of 200000 compute units",
        "Program TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb success"
      ],
      "replacementBlockhash": {
        "blockhash": "6oFLsE7kmgJx9PjR4R63VRNtpAVJ648gCTr3nq5Hihit",
        "lastValidBlockHeight": 381186895
      },
      "returnData": null,
      "unitsConsumed": 1714
    }
  },
  "id": 1
}
```

{% endtab %}
{% endtabs %}