# FastSpring

Source: https://kart.bnomei.com/docs/providers/fastspring
Updated: 2025-08-08T14:18:12+00:00
Summary: Learn how to integrate FastSpring with Kirby CMS using Kart: set provider, define virtual fields, add API creds & customize checkout via callbacks.

> This provider intends to import existing products from FastSpring into Kirby once and then switch to another provider.

### Using the provider

Path: site/config/config.php  
Code (php):  
```
<?php

return [
   'bnomei.kart.provider' => 'fastspring',
   // other options
];
```

  
## Virtual Fields

You can define which fields are treated as purely virtual and fetched from the provider ignoring any changes you make within the panel.

Code (php):  
```
<?php

return [
 'bnomei.kart.providers.fastspring.virtual' => true,
 // 'bnomei.kart.providers.fastspring.virtual' => ['raw', 'title', 'description', 'gallery'],

 // other options
];
```

  
## API Credentials

![](https://kart.bnomei.com/media/pages/media/fd33071f03-1746706063/fastspring-1920x.webp)  
Path: .env  
Code (plaintext):  
```
FASTSPRING_STORE_URL=XXX
FASTSPRING_USERNAME=YYY
FASTSPRING_PASSWORD=ZZZ
```

  
## Customzing the Checkout

You can use callbacks to customise both the checkout process and each line item. The returned arrays from your callbacks will be merged with the defaults created by the plugin for this provider, allowing you to override those defaults. Check the relevant PHP class and the linked online documentation for the provider to learn more about the expected data structure.

Code (php):  
```
<?php

return [
    'bnomei.kart.providers.fastspring.checkout_options' => function (\Bnomei\Kart\Kart $kart) {
        // configure the checkout based on current kart instance
        // https://developer.fastspring.com/docs/storefront-urls#link-to-your-checkouts-with-the-api
        return [];
    },
    'bnomei.kart.providers.fastspring.checkout_line' => function (\Bnomei\Kart\Kart $kart, \Bnomei\Kart\CartLine $line) {
        // add custom data to the current checkout line
        return [];
    },
    // other options
];
```