SwftSubscriptions

Subscription product support for Swft Checkout. Enables WooCommerce Subscriptions (or WooCommerce Simple Subscriptions) products to go through the Swft checkout flow, with recurring billing handled via Stripe’s subscription APIs.

What it does

• Detects subscription products in the cart
• Passes subscription billing interval, period, and trial data through the session
• Creates a Stripe SetupIntent (for future billing) instead of a PaymentIntent when the cart is subscription-only
• Creates a PaymentIntent + SetupIntent for mixed carts (subscription + regular products)
• After payment, creates a Stripe Customer and Subscription
• Syncs subscription state to WooCommerce Subscriptions

Compatibility

Plugin	Status
WooCommerce Subscriptions	Supported
WooCommerce Simple Subscriptions	Supported
YITH WooCommerce Subscriptions	Partial (contact support)

Installation

1. Install and activate WooCommerce Subscriptions (or compatible plugin)
2. Download swft-subscriptions.zip from swft.co.uk/modules
3. Install and activate SwftSubscriptions

Configuration

Go to WooCommerce → Settings → SwftSubscriptions:

Setting	Option	Default
Enable trial period display	swft_subs_show_trial	yes
Trial label	swft_subs_trial_label	Free for {days} days, then {price}/{period}
Cancel at period end	swft_subs_cancel_at_period_end	no

Extension data

SwftSubscriptions adds the following to extensions.subscription in the session when the cart contains a subscription product:

{
  "product_id": 101,
  "type": "subscription",
  "billing_period": "month",
  "billing_interval": 1,
  "trial_length": 14,
  "trial_period": "day",
  "initial_amount": 0,
  "recurring_amount": 2999,
  "currency": "GBP",
  "sign_up_fee": 0
}

The checkout frontend reads this to:

• Replace the pay button label: Start free trial / Subscribe — £29.99/mo
• Show a trial period notice below the pay button
• Use a SetupIntent flow instead of PaymentIntent for zero-amount initial charges

Payment flow

Regular subscription (no trial)

SetupIntent created → customer enters card → Stripe charges initial amount
  → Stripe Customer created → Stripe Subscription created
  → WooCommerce Subscription activated

Trial subscription (initial amount = 0)

SetupIntent created → customer enters card → card saved, no charge
  → Stripe Customer created → Stripe Subscription created with trial_end date
  → Trial billing fires automatically at trial end
  → WooCommerce Subscription activated

Mixed cart (subscription + regular products)

PaymentIntent created for regular items → SetupIntent for subscription card
  → Both confirmed in one Stripe Elements flow
  → Regular order + Subscription created in WooCommerce

Order meta

Meta key	Value
_swft_ext_subscription	Full subscription data as JSON
_swft_stripe_customer_id	Stripe Customer ID
_swft_stripe_subscription_id	Stripe Subscription ID

PHP hooks

// Modify subscription extension data before it is sent
add_filter( 'swft_subscription_extension_data', function( array $data, WC_Product $product ): array {
    return $data;
}, 10, 2 );

// Fired after the Stripe Subscription is created
add_action( 'swft_subscription_created', function( string $stripe_sub_id, int $wc_order_id ): void {
    // sync to your CRM
}, 10, 2 );

// Fired when a subscription renewal payment succeeds (Stripe webhook)
add_action( 'swft_subscription_renewed', function( string $stripe_sub_id, int $wc_order_id ): void {
    // update member access
}, 10, 2 );

// Fired when a subscription is cancelled
add_action( 'swft_subscription_cancelled', function( string $stripe_sub_id, int $wc_subscription_id ): void {
    // revoke access
}, 10, 2 );