Production-ready guidance for merchants integrating A55’s risk signals and device fingerprint to increase approval rates and reduce fraud.

🚀 Overview

A55’s Anti-Fraud layer enriches each payment with behavioral and contextual data, allowing precise risk evaluation before authorization or 3DS.
By sending both device_info and antifraud_info, merchants enable smarter scoring — fewer false declines, lower chargebacks, and a frictionless checkout.

⚙️ 1. How Our Risk Engine Works

Our system evaluates each charge using five core dimensions:

Possible outcomes:

• risk_approved → proceeds to authorization (and 3DS if configured)
• risk_challenge → triggers extra verification (e.g., 3DS challenge)
• risk_declined → blocked before authorization

💡

Goal: Reduce issuer declines and chargebacks while preserving a smooth checkout experience.

🧠 2. Why antifraud_info Matters

The antifraud_info block provides behavioral and historical context about the buyer and their relationship with the merchant.
This data empowers our models to differentiate trusted customers from high-risk profiles, resulting in:

• ⚡ Higher approval rates for legitimate users
• 🚫 Fewer chargebacks and fraud attempts
• 🤝 Smarter 3DS routing (only when needed)

Recommended Fields

Tip: Even partial antifraud_info greatly improves accuracy — send what you have!

🔍 Device Fingerprint Capture with A55Pay SDK

You can automatically capture the device fingerprint using the A55Pay SDK.
This fingerprint helps enhance fraud detection and improve 3DS approval rates.

1. Include the SDK Script

Add the following <script> tag to your checkout page before your main script:

<script src="https://cdn.jsdelivr.net/npm/a55pay-sdk"></script>

2. Capture the Device Fingerprint

Once the page loads, the SDK will automatically generate a unique device_id.
You can log it, store it temporarily, or attach it to your payment payload.

Example:

<script>
  // Automatically display the device_id when the page loads
  window.addEventListener('load', function() {
      setTimeout(function() {
          const deviceId = A55Pay.getDeviceId(); // Example: db2c5ad0-6fe6-4821-baec-0d9e67cdab5d
          console.log('🚀 SDK Loaded! Device ID automatically generated:', deviceId);
      }, 1000); // Wait 1 second to ensure the SDK is fully loaded
  });
</script>

3. Sending the Fingerprint in the Charge Payload

When creating a charge, include the generated device_id inside the device_info field of your payload.

Example Payload:

const chargePayload = {
  // Other fields...
  device_info: {
    device_id: deviceId // ! IMPOTANT SEND FINGERPRINT IN PAYLOAD CHARGE
  }
  // ...
};

🧩 4. Example Payload

{
  "merchant_id": "fc2226b9-cd39-4dbe-8314-c03279404049",
  "wallet_uuid": "d02995ef-3c17-4816-a81c-af234f840f57",
  "type_charge": "credit_card",
  "currency": "BRL",
  "description": "Order #A55-83921",
  "items": [
    {
      "sku": "CABXIN-HDMI-2M",
      "code": "HDMI-2025-001",
      "name": "HDMI Cable 2m 4K",
      "quantity": 1,
      "unit_amount": 129.9,
      "total_amount": 129.9
    }
  ],
  "payer_name": "John Souza",
  "payer_email": "[email protected]",
  "payer_tax_id": "38899334821",
  "payer_cell_phone": "559999999999",
  "payer_address": {
    "street": "Av. Paulista",
    "address_number": "1578",
    "neighborhood": "Bela Vista",
    "city": "São Paulo",
    "state": "SP",
    "postal_code": "01311-000",
    "country": "BR"
  },
  "device_info": {
    "device_id": "db2c5ad0-6fe6-4821-baec-0d9e67cdab5d", // ! IMPOTANT SEND FINGERPRINT IN PAYLOAD CHARGE
    "ip_address": "177.92.34.56",
    "user_agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64)",
    "http_browser_language": "pt-BR",
    "http_browser_screen_width": "1920",
    "http_browser_screen_height": "1080",
    "http_browser_javascript_enabled": true
  },
  "antifraud_info": {
    "sales_channel": "web",
    "cardholder_logged_in": true,
    "cardholder_since_days": 365,
    "days_since_first_purchase_cardholder": 120,
    "days_since_last_purchase_cardholder": 30,
    "card_replacement_count": 1,
    "profile_update_days_count": 45,
    "profile_data_changed": 0,
    "profile_field_changed": "email",
    "purchase_history": 8,
    "merchant_customer_since_days": 720,
    "days_since_first_purchase_merchant": 700,
    "days_since_last_purchase_merchant": 5
  }
}

🧭 5. Best Practices

• ✅ Always send device_info.device_id
• ✅ Normalize numeric fields (days as integers)
• ✅ Send boolean values as true or false (never strings)
• ✅ Use consistent channel naming (web, app, pos)
• ✅ Do not log sensitive fields (email, tax ID) in plain text
• ✅ Test different risk profiles in sandbox

🧰 6. Operational Recommendations

• Include cardholder_logged_in and cardholder_since_days — they are top predictors of trust.
• For marketplaces, use merchant_customer_since_days to evaluate buyer–seller relationship.
• Update profile_update_days_count whenever key customer data changes.
• If you maintain your own risk/trust score, include it as a custom key (e.g. "internal_trust_score": 87).

🔒 7. Security & Compliance

• Transmit all risk data over HTTPS/TLS only.
• Treat antifraud fields as personal data (PII) under LGPD/GDPR.
• Retain data only for fraud prevention purposes.
• Hash or tokenize identifiers in logs.

✅ 8. Checklist Before Go-Live

🧾 Summary

Integrating device_info and antifraud_info transforms your checkout into a data-driven risk-aware flow.
The result:

• More approvals ⚡
• Fewer chargebacks 🚫
• A seamless customer experience 🤝

📘 Learn more:
For extended documentation and SDK guides, visit: docs.a55.tech