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This guide walks you through integrating Pillar8 into your checkout to start receiving decision packages. The integration is lightweight and requires no changes to your existing payment stack.
1

Add Pillar8 to Checkout

Install the Pillar8 client in your checkout environment.The component:
  • Captures checkout context (device, country, cart, payment methods)
  • Sends a request to the Pillar8 decision engine
  • Receives a decision package in real time
2

Call the Optimize API

Your checkout integration sends a request to:POST /api/shopify/checkout-optimize

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Example Request

{
  "shop_domain": "example.myshopify.com",
  "cart_value": 85,
  "currency_code": "EUR",
  "country_code": "DE",
  "device_type": "mobile",
  "checkoutToken": "abc123",
  "default_fops": ["card", "paypal", "klarna"],
  "presented_payment_methods": ["card", "paypal", "klarna"]
}
3

Receive Decision Package

Pillar8 returns a decision package for the checkout session.

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Example Response

{
  "status": "ok",
  "ab_variant": "optimize",
  "was_optimized": true,
  "shadow_engine": {
    "scored": [
      { "code": "paypal", "score": 0.82 },
      { "code": "card", "score": 0.74 }
    ]
  },
  "gating_passed": true
}
4

Apply the Decision

Use the decision package to:
  • Display an advisory recommendation to the shopper
  • Highlight or emphasize specific payment methods
  • Adjust checkout behavior
5

Send Transaction Outcome (Webhook)

Configure your backend to send transaction outcomes to Pillar8.POST /api/shopify/webhooks/order-completedThis enables Pillar8 to:
  • Learn from actual payment outcomes
  • Improve future decisions
  • Measure impact
Typical integration time: a few hours to a couple of days

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What Does Not Change

  • Your PSP integrations remain unchanged
  • Your orchestration layer remains unchanged
  • Your payment routing remains unchanged
Pillar8 operates before payment execution.

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Next Steps

  • See API for full endpoint definitions
  • Review Architecture to understand system flow
  • Check Platforms → Shopify for platform-specific details