# Private Transactions

The **`blxr_private_tx`** endpoint allows users to send a single transaction that is added directly to the blocks generated by block builders.

\
Private txs are automatically enrolled in the BackRunMe service and will pay back searchers a portion of the profit. The endpoint returns a transaction hash.

This service is available via both the **Cloud API** and **Gateway API**.

## Submission Endpoint

* Method: `blxr_private_tx`
* Endpoint: `api.blxrbdn.com` (Cloud API)
* Gateway API Endpoint: `127.0.0.1:28333/ws` (assumes WebSocket port 28333)
* Request type: *`HTTPS,WSS`*

### Parameters

| Parameter                                                                                      | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| ---------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **`transaction`**                                                                              | *\[Mandatory]* Raw transaction bytes without **`0x`** prefix.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| **`timeout`**                                                                                  | *\[Optional]* An integer value that represents the time, in seconds, needed to wait for a Private Transaction to be included in a block. If omitted, it defaults to 0. If **`timeout`** is not 0 and the transaction is not mined after the timeout value, it will be sent publicly. If the **`timeout`** is 0, no public transaction will be sent.                                                                                                                                                                                                                                                                                                            |
| **`mev_builders`**                                                                             | <p><em>\[Optional, default: <code>all</code> builder]</em> A dictionary of MEV builders that should receive the private transaction. Please provide empty string as signature for each builder. Possible MEV builders are:</p><ul><li><code>flashbots</code>: flashbots builder</li><li><code>beaverbuild</code>:  <a href="https://beaverbuild.org/">beaverbuild.org</a></li><li><code>rsync-builder</code> : <a href="https://rsync-builder.xyz">rsync-builder.xyz</a></li><li><code>all</code>: all builders</li></ul><p>Traders can refer to <a href="../submit-bundles/list-of-external-builders">List of External Builders page</a> for a full list.</p> |
| **`node_validation`**                                                                          | *\[Optional, default: false]* Transaction would be validated by a blockchain node, and Cloud-API returns an error message (e.g. "invalid sender" or "nonce too low") in case the raw transaction byte fails validation check.                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| [**`priority_fee_refund`**](https://docs.bloxroute.com/eth/submit-bundles/priority-fee-refund) | *\[Optional, default: False]* A boolean flag indicating if the bundle should be sent just to a single block builder who is participating in the priority fee refund program. Please refer to Priority Fee Refund for details of the priority fee refund program.                                                                                                                                                                                                                                                                                                                                                                                               |
| **`refund_recipient`**                                                                         | *\[Optional]* A string representing the wallet address to receive refund when `priority_fee_refund` flag is enabled.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
| `backrunme_reward_address`                                                                     | *\[Optional]*  String – valid ETH address specifying where backrun rewards should be shared - See [Backrunme program](https://docs.bloxroute.com/backrunme-program)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |

### Example

{% tabs %}
{% tab title="HTTPS - Cloud API" %}

```bash
curl https://api.blxrbdn.com \
    --insecure \
    -X POST \
    -H "Content-Type: application/json" \
    -H "Authorization: <YOUR-AUTHORIZATION-HEADER>" \
    -d '{
         "id": "1", 
         "method": "blxr_private_tx", 
         "params": {
            "transaction": "f86b0184...e0b58219",
            "mev_builders": {
                "flashbots": "",
                "beaverbuild": "",
                "all": ""
	     }
          }
        }'
```

{% endtab %}

{% tab title="wscat - Cloud API " %}

```bash
wscat -c wss://api.blxrbdn.com/ws --header "Authorization: <YOUR-AUTHORIZATION-HEADER>" --no-check
> {
	"jsonrpc": "2.0", 
	"id": 1, 
	"method": "blxr_private_tx", 
	"params": {
		"transaction": "f86b0184...e0b58219",
		"mev_builders": {
			"bloxroute": "",
			"flashbots": "",
			"beaverbuild": "",
			"all": ""
		}
	}
}
```

{% endtab %}
{% endtabs %}

#### Response

{% tabs %}
{% tab title="Cloud-API" %}

```bash
{
    "jsonrpc": "2.0", 
    "id": "1", 
    "result": "0xffd59870844e5...bfa54a69"        
}    
```

{% endtab %}
{% endtabs %}