> For the complete documentation index, see [llms.txt](https://docs.4p.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.4p.finance/en/webhook/understanding-notification.md).

# Understanding notification

This page is intended to introduce webhook notifications. This feature is available in your **4P Finance** account's API and lets you view the POST requests that **4P Finance** sends to the return URL defined by the integrator. This POST contains only one piece of information: a notification token.

Additional information about setting up the notification URL and the mechanics involved in querying the details of a notification can be found on the [Retrieving notification data](broken://pages/82b390e6397a9e677eaaac08a77cca4fa8cd4674) page.

Just because the POST is sent *successfully (200)* to your return URL does not, by itself, mean the flow has completed fully. When you receive the POST, you'll need to query that notification's information.

{% hint style="danger" %}
Warning! The POST that **4P Finance** sends to your return URL **does not contain the transaction data, only the notification token.** All information about that transaction will be returned once you consume the `GET /notification/:token` endpoint.
{% endhint %}

The notification process works as a "two-way street" — a POST request is made to your return URL once the Pix payment is confirmed, and then your system, holding the notification token, sends a request to consume the `GET /pix/notification/:token` endpoint, where `:token` is the notification token contained in the POST that was sent.

The flow follows this order:

1. 4P Finance will send an HTTP POST request to the callback URL (webhook) provided when the transaction was created.

This notification is triggered automatically after:

#### On-ramp:

1. Payment confirmation; and
2. Confirmation that the cryptocurrency has been sent on the blockchain.

#### Off-ramp:

1. Confirmation that the cryptocurrency has been received.

The POST will contain only a notification token, allowing your system to validate and process the operation's final status securely and automatically.

As soon as you receive the POST request, make a `GET` request to the `/notification/:token` route, where `:token` will be the notification token we sent you.

{% hint style="info" %}
By making new `GET` requests to `/notification/:token`, you'll receive updates about the transaction whenever there's a change, such as in the status: `pending`, `processing`, `success` or `error`.
{% endhint %}

{% hint style="warning" %}
**Important!** If your system queries the token we sent, we consider the notification to have been successfully delivered. If it isn't queried, we will keep retrying for up to 5 days.

In other words, if there's a request to the `GET /notification/:token` endpoint, we understand that you received the POST with the notification token and queried it, receiving in the response all the informational data about the transaction's confirmation.
{% endhint %}

## Security

To ensure secure communication between servers, your callback (webhook) URL is required to use the HTTPS protocol.

**Notifications are sent from the following outbound IPs:**

44.196.63.157

We recommend configuring your infrastructure to accept requests only from this IP (allowlist), ensuring that only our servers can access your endpoint.

We strongly recommend that your system:

* Generate a unique token per transaction on your backend;
* Include that token as a parameter in the notification URL (`notification_url`) when the transaction is created;
* Use that token to validate the authenticity of notifications received via POST;
* Validate that the request originated from the specified IP.

This way, when receiving a notification from 4P Finance, your system will be able to:

* Confirm that the request originated from our servers;
* Validate the token received and ensure that the request corresponds exactly to the expected transaction.

**Example webhook URL (`notification_url`):**

{% hint style="info" %}
`https://webhook.mycompany.com/pix/?custom_id=12345&your-token=eae1fe563265167f8d88aec8cd4a7609`
{% endhint %}