> ## Documentation Index
> Fetch the complete documentation index at: https://protochain.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# CompileTransaction

> Serialize a draft transaction to wire format and fetch a recent blockhash.

Compiles a DRAFT transaction to wire format, transitioning it to COMPILED state. If `recent_blockhash` is not supplied, the service fetches the latest blockhash automatically — this is the standard pattern.

<Note>
  After compilation, instructions cannot be added or removed. The `instructions` field on the returned transaction is no longer the source of truth — the transaction is now encoded in `data`.
</Note>

## Request

<ResponseField name="transaction" type="Transaction (object)" required>
  Draft transaction in DRAFT state containing the instructions to compile.

  <Expandable title="Transaction fields">
    <ResponseField name="instructions" type="SolanaInstruction[]">
      Instructions to include in the transaction (only relevant in DRAFT state).
    </ResponseField>

    <ResponseField name="config" type="TransactionConfig (object)">
      Optional compute budget configuration.

      <Expandable title="TransactionConfig fields">
        <ResponseField name="compute_unit_limit" type="uint32">
          Max compute units for the transaction.
        </ResponseField>

        <ResponseField name="compute_unit_price" type="uint64">
          Price per compute unit in microlamports.
        </ResponseField>

        <ResponseField name="priority_fee" type="uint64">
          Priority fee in lamports.
        </ResponseField>

        <ResponseField name="skip_preflight" type="bool">
          If true, skip preflight simulation before submission.
        </ResponseField>

        <ResponseField name="skip_account_validation" type="bool">
          If true, skip account validation during submission.
        </ResponseField>
      </Expandable>
    </ResponseField>
  </Expandable>
</ResponseField>

<ResponseField name="fee_payer" type="Base58-encoded public key (string)" required>
  Address that will pay transaction fees.
</ResponseField>

<ResponseField name="recent_blockhash" type="Base58-encoded string (optional)">
  Optional. If empty, the service fetches the latest blockhash. Supply only for durable nonce transactions.
</ResponseField>

## Response

<ResponseField name="transaction" type="Transaction (object)">
  The compiled transaction in COMPILED state.

  <Expandable title="Transaction fields">
    <ResponseField name="state" type="TransactionState enum">
      TRANSACTION\_STATE\_COMPILED (2) after successful compilation.
    </ResponseField>

    <ResponseField name="data" type="string">
      Compiled transaction bytes. The source of truth once the transaction is in COMPILED or later state.
    </ResponseField>

    <ResponseField name="fee_payer" type="Base58-encoded string">
      The fee payer address.
    </ResponseField>

    <ResponseField name="recent_blockhash" type="string">
      The blockhash used during compilation. Transactions expire \~150 slots after their blockhash.
    </ResponseField>
  </Expandable>
</ResponseField>

## Code Examples

<CodeGroup>
  ```go Go theme={null}
  // Assume txn is a Transaction in DRAFT state with instructions already set
  resp, err := client.CompileTransaction(ctx, &transaction_v1.CompileTransactionRequest{
      Transaction: txn,
      FeePayer:    "YourFeePayer111111111111111111111111111111",
      // recent_blockhash omitted — service fetches latest automatically
  })
  if err != nil {
      log.Fatal(err)
  }
  compiled := resp.Transaction
  fmt.Printf("State: %v\n", compiled.State)
  ```

  ```rust Rust theme={null}
  let response = client.compile_transaction(tonic::Request::new(CompileTransactionRequest {
      transaction: Some(txn), // DRAFT state transaction
      fee_payer: "YourFeePayer111111111111111111111111111111".to_string(),
      recent_blockhash: String::new(), // omit — service fetches latest
      ..Default::default()
  })).await?;
  let compiled = response.into_inner().transaction.unwrap();
  println!("State: {:?}", compiled.state);
  ```

  ```typescript TypeScript theme={null}
  const req = new CompileTransactionRequest();
  req.setTransaction(txn); // DRAFT state transaction
  req.setFeePayer("YourFeePayer111111111111111111111111111111");
  // recent_blockhash omitted — service fetches latest
  client.compileTransaction(req, (err, response) => {
    const compiled = response.getTransaction();
    console.log("State:", compiled.getState());
  });
  ```
</CodeGroup>