# Checkout validation

When a user attempts to upgrade or change their subscription using the Bunny portal we call this a checkout.

In some cases you might want to check if the plan or quantity change should be allowed before letting the user proceed.

{% hint style="warning" %}
For example, you have a customer on a plan that includes 10 users and they have created 10 users on your platform. If they then tried to downgrade to a plan that only had 5 users you could use this webhook to block the change and provide a message explaning that they need to delete or deactivate some users before they can proceed with the change.
{% endhint %}

### Enabling checkout validation

To enable this webhook you will need to ensure that you have [enabled a webhook endpoint for your platform in Bunny](/developer/webhooks/webhooks.md).

Then on your platform enable the Checkout validation option.

<figure><img src="/files/DdXYIFuqH44p4eEfISKd" alt="" width="206"><figcaption></figcaption></figure>

### Checkout validation webhook payload

The payload that will be sent will contain information about the tenant on your platform that is requesting a change and the features and quantities that they will be change to.

```json
{
  "type": "CheckoutValidation",
  "payload": {
    "tenant": {
      "id": 132,
      "code": "8c665dde-69ae-4c53-990b-3d19bf71791e",
      "name": "Superdesk Inc"
    },
    "change": {
      "features": [
        {
          "code": "users",
          "name": "Users",
          "value": "",
          "quantity": 10,
          "plan": {
            "code": "enterprise",
            "name": "Enterprise"
          },
          "price_list": {
            "code": null,
            "name": "Enterprise Monthly"
          }
        },
        {
          "code": "widgets",
          "name": "Widgets",
          "value": "100",
          "quantity": 100,
          "plan": {
            "code": "enterprise",
            "name": "Enterprise"
          },
          "price_list": {
            "code": null,
            "name": "Enterprise Monthly"
          }
        }
      ]
    }
  }
}
```

If you wanted to validate the number of users you would use the Tenant code to look up the relevant tenant in your application, get a count of the users and then compare this to the number of users requested in the checkout validation payload.

### Responding to the webhook

If you opt-in to using the checkout validation webhook you must respond within 5 seconds with one of the following decisions.

#### Change approved

The user will be allowed to continue with the subscription change.

```
HTTP STATUS CODE: 200 - OK
```

No response body is required and will be ignored if provided.

#### Change denied

The user will not be able to continue and will be displayed the error message that you provide.

```
HTTP STATUS CODE: 422 - Unprocessable Content
```

The required JSON response body is an array of strings that explain why the subscription change is not possible.

{% code overflow="wrap" %}

```json
[
   "You have too many users to downgrade to this plan. Please remove some users and try again."
]
```

{% endcode %}

<figure><img src="/files/sYkiHq9hwo7KOJini5qM" alt="" width="375"><figcaption><p>The response from a denied checkout validation is displayed to the user.</p></figcaption></figure>


---

# Agent Instructions: Querying This Documentation

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```
GET https://docs.bunny.com/developer/webhooks/checkout-validation.md?ask=<question>
```

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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.