simulateTransaction

Dry-run a Solana transaction over rpc edge to get logs, compute units, and errors before sending.

simulateTransaction runs a transaction against the current bank without submitting it. Use it to catch errors, read program logs, and measure compute-unit usage before you spend a fee. On shared plans it has its own safety limits (see rate limits).

Request

curl -s https://rpc.rpcedge.com \
  -H 'content-type: application/json' \
  -H 'x-api-key: YOUR_UUID_KEY' \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "simulateTransaction",
    "params": ["<base64-encoded-tx>", { "encoding": "base64", "commitment": "processed", "replaceRecentBlockhash": true }]
  }'

Parameters

Position	Name	Type	Notes
`0`	`transaction`	`string`	Serialized transaction (signing optional unless `sigVerify` is set).
`1`	`config`	`object`	Optional. Fields below.

Field	Type	Notes
`encoding`	`string`	`base64` (recommended) or `base58`.
`commitment`	`string`	Bank state to simulate against.
`sigVerify`	`bool`	Verify signatures. Cannot be used with `replaceRecentBlockhash`.
`replaceRecentBlockhash`	`bool`	Swap in a fresh blockhash before simulating - avoids "blockhash not found".
`accounts`	`object`	`{ addresses, encoding }` to return post-simulation account state.

Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "context": { "slot": 429641447 },
    "value": {
      "err": null,
      "logs": ["Program 11111111111111111111111111111111 invoke [1]", "Program ... success"],
      "unitsConsumed": 4821,
      "accounts": null,
      "returnData": null
    }
  }
}

Field	Meaning
`err`	`null` on success; otherwise the on-chain error the transaction would hit.
`logs`	Program log lines - the fastest way to debug a failing instruction.
`unitsConsumed`	Compute units used - size your compute-unit limit from this.
`returnData`	Program return data, if any.