You're ready to latch onto Events if you've...

  1. Configured Snipcart to post to your Craft webhook
  2. Determined what you're listening for and what you need to do
  3. Established your own plugin or module for project-specific business logic

Let's say, for example, that we'd like to offer custom shipping rates depending on the specifics of an order. We've configured our webhook and a custom module.

Customize Shipping Rates at Checkout#

Snipcart sends a webhook request to see if we want to provide shipping rates. We'll listen for this and respond in the format Snipcart expects. The Event will come with the nearly-completed order and all its details, so all you need is to tell Craft that you'd like to respond to it and provide your own logic to send back rates.

Register an event listener for EVENT_BEFORE_RETURN_SHIPPING_RATES in your module's init() method:

public function init(): void

    Event::on(Shipments::class, Shipments::EVENT_BEFORE_RETURN_SHIPPING_RATES, function(ShippingRateEvent $event) {
        $event->rates = $this->modifyShippingRates(

This calls our own custom function called modifyShippingRates(), which looks at order details and gives back an array of rates. (This logic could all live inside of function(WebhookEvent $event) {}, but it'll be tidier to separate things a bit.)

That function, also in our base Module class—even though it could live anywhere—might look like this:

private function modifyShippingRates($rates, $order, $package): array
    // don't allow any rates that include these strings
    $disallow = [
        'Flat Rate Envelope',
        'Regional Box A',

    $filteredRates = []; // we'll populate and return this

    foreach ($rates as $rate) {
        foreach ($disallow as $notAllowed) {
            // allow the rate if the disallowed string is *not* in the rate description
            if (stripos($rate->description, $notAllowed) === false) {
                $filteredRates[] = $rate;

    return $filteredRates;

The function above will filter out any existing rates whose description include Flat Rate Envelope or Regional Box A.

Add a Rate for Specific Orders#

We could just as easily add our own rate. Here, we'll add a special shipping option if someone has ordered only a trombone.

private function modifyShippingRates($rates, $order, $package): array
    $numberOfOrderItems = count($order->items);

    if ($order->items === 1) {
        foreach ($order->items as $item) {
            if ($item->name === 'Trombone')  {
                $rates[] = new ShippingRate([
                    'cost' => 12.99,
                    'description' => 'Special Trombone Shipping',

    return $rates;

The order details include a lot of information, so you could tailor rates based on the customer, the shipping destination, the order items, or a whole bunch of other things you'll see in the Snipcart Order model.

See the Events reference for a complete list of Events you can utilize.

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