# Automatic POSTBACK

After successful payment execution, a POST request with information about the payment is sent to the notification URL specified in the project settings.

## Request parameters

| Parameter name | Data type | Value                                                                                                                       | Example                                                                                                              | Description                      |
| -------------- | --------- | --------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------- | -------------------------------- |
| status         | string    | success                                                                                                                     | success                                                                                                              | Request execution status         |
| invoice\_id    | string    | id                                                                                                                          | DZLF4212                                                                                                             | Unique payment identifier        |
| amount\_crypto | decimal   | sum                                                                                                                         | 0.4567                                                                                                               | Payment amount in cryptocurrency |
| currency       | string    | <p>BTC</p><p>LTC</p><p>ETH</p><p>USDT\_TRC20<br>USDT\_ERC20<br>USDC\_TRC20<br>USDC\_ERC20<br>TUSD\_TRC20<br>TUSD\_ERC20</p> | BTC                                                                                                                  | Currency code                    |
| order\_id      | string    | id                                                                                                                          | ORD99999                                                                                                             | Store order identifier           |
| token          | string    | token                                                                                                                       | eyJ0eXAiOiJKV1QiLCJhbGciOiJIAcI1NiJ9.eyJpZCI6MTMsImV4cCI6MTYzMTc4NjQyNn0.HQavV3z8dFnk56bX3MSY5X9lR6qVa9YhAoeTEHkaAzs | JWT token                        |

{% hint style="info" %}
JWT token — response signature from the server. It is signed with a secret key generated in the project settings. Additionally, UUID of the invoice is added to the token. The token is valid for 5 minutes after the notification is created. It is generated each time a payment notification is sent.

The encryption algorithm is HS256.
{% endhint %}

## Response example

```json
{
   "status": "success",
   "invoice_id": “DZLF4212”,
   "amount_crypto": 0.4567,
   "currency": “BTC“,
}
```

## Example of POSTBACK processor

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

```python
from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/postback', methods=['POST'])
def handle_postback():
    data = request.json
    status = data.get('status')
    invoice_id = data.get('invoice_id')
    amount_crypto = data.get('amount_crypto')
    currency = data.get('currency')
    order_id = data.get('order_id')
    token = data.get('token')
    
    # ... your code for processing postback ...
    
    return jsonify({'message': 'Postback received'}), 200

if __name__ == '__main__':
    app.run(port=5000)
```

{% endtab %}

{% tab title="JavaScript" %}

```javascript
const express = require('express');
const app = express();

app.use(express.json());

app.post('/postback', (req, res) => {
    const { status, invoice_id, amount_crypto, currency, order_id, token } = req.body;
    
    // ... your code for processing postback ...
    
    res.json({ message: 'Postback received' });
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});
```

{% endtab %}
{% endtabs %}