Show shoppers their top 3 cards at checkout.

SuperPay in one paragraph

SuperPay is the AI-powered payment intelligence layer for the modern wallet. On the consumer side we tell shoppers which card to use at every merchant, surface unused perks, and forecast their best path to maximum rewards. On the merchant side, our Checkout API adds a smart card-recommendation widget to your checkout — surfacing the top 3 cards by reward rate for this purchase as stacked, individually-tappable rows (best first). No integration with your payment processor required.

What you get as a partner

• A REST API that returns the top 3 ranked card recommendations for any checkout session.
• A drop-in widget (one <script> tag) that renders the top 3 cards as stacked, tappable rows on your existing checkout.
• Sandbox + production environments with revocable, scoped API keys and origin allowlisting.
• Distribution to the SuperPay shopper base — featured placement, push, and in-app discovery.
• A real human on launch: hello@superpayrewards.com.

Reward visibility drives purchase confidence.

Shoppers with multiple credit cards face decision fatigue at checkout. Which card should I use? Am I missing rewards? That hesitation costs you conversions. SuperPay removes the question entirely.

You're a great fit if…

• You sell direct to consumer online and protect a brand price.
• You run premium, considered-purchase products (apparel, beauty, electronics, travel, subscriptions) where a 10–20% discount damages positioning.
• You have an email or SMS list you want to reactivate without resorting to a code drop.
• You want category-level distribution — appearing in front of shoppers who are already optimizing their card spend.

Probably not a fit (yet)

• Pure marketplaces where you don't control checkout.
• Hyper-low-margin commodity goods where every dollar of reward eats the unit.
• Regulated categories where promotional rewards trigger compliance review (we'll talk first).

One call. That's the integration.

1. Request a recommendation by passing the cart amount and category (or MCC) to /v1/recommend — server-side or directly from the widget.
2. Render the recommendation on your checkout via the drop-in widget (one <script> tag), or your own UI built on the JSON response.
3. Shopper picks up the recommended card and completes purchase through your existing processor. Their card issuer awards the reward directly, on the issuer's normal cycle.

Lifecycle of a single recommendation

Get to a working sandbox in under 15 minutes

Step 1 — Get your sandbox key

Visit /for-merchants, fill in your business name, contact email, and store origins (the domains where the widget will be embedded). You'll receive a verification email — click it and your sandbox key is provisioned immediately.

Step 2 — Get a recommendation

Call POST /v1/recommend with the cart amount and either an MCC or a category. You can call this server-to-server, or skip it entirely and let the widget call it for you (Step 3).

curl -X POST https://superpayrewards.com/v1/recommend \
  -H "Authorization: Bearer sp_test_..." \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 87.45,
    "mcc": "5411",
    "merchant_name": "Whole Foods Market"
  }'

Response (abridged):

{
  "recommendation_id": "9f8...",
  "top_cards": [
    {
      "rank": 1,
      "name": "Blue Cash Preferred® Card from American Express",
      "reward_rate": 6,
      "estimated_reward_cents": 524,
      "estimated_reward_display": "$5.24",
      "reason": "6% on groceries",
      "apply_url": "https://..."
    },
    { "rank": 2, "name": "Citi Custom Cash", "reward_rate": 5, ... },
    { "rank": 3, "name": "Amex Gold",         "reward_rate": 4, ... }
  ],
  "top_card":   { /* DEPRECATED — same as top_cards[0]. Removed one release after this one. */ },
  "alternates": [ /* DEPRECATED — top_cards[1..] in lighter shape. */ ],
  "display": {
    "headline": "Top 3 cards for this purchase",
    "subline": "Top pick: Blue Cash Preferred · 6% back"
  }
}

Migrating? Read top_cards[] instead of top_card + alternates — every entry has the same shape and includes rank, image_url, and apply_url. The deprecated fields will be removed one release after this one ships.

Step 3 — Embed the widget on your checkout

Drop a mount <div> with the cart context, then load /v1/widget.js once anywhere on the page. The widget calls /v1/recommend for you and renders the top-3 cards (stacked rows, best first, each row tappable to apply).

<div data-superpay-recommend
  data-amount="87.45"
  data-mcc="5411"
  data-merchant="Whole Foods Market"
  data-superpay-effective-cost-target="#sp-effective-cost"></div>

<!-- Optional: empty target the widget fills with
     "Effective cost with SuperPay: $X.XX — after $Y.YY rewards".
     Place it directly under your Pay / Place Order button. -->
<div id="sp-effective-cost"></div>

<script src="https://superpayrewards.com/v1/widget.js"
  data-key="sp_test_..." async></script>

Effective-cost line. The data-superpay-effective-cost-target attribute is opt-in — leave it off and nothing extra renders. When set, the widget fills the referenced element with a single muted line showing the cart total minus the top pick's estimated rewards. The line is gated so it never lies to a shopper: it only renders when the top pick is a cashback card with a positive estimated reward, a known cart total, and the resulting effective cost is non-negative (rewards never shown as exceeding the order total). Points/miles cards, $0 reward estimates, missing amounts, or a negative effective cost all suppress the line silently.

Step 4 — That's it. The shopper does the rest.

The shopper picks up the recommended card and pays through your existing processor. Their card issuer awards the reward directly under their cardholder agreement — there's no SuperPay-side confirmation, no webhook, no payout to wire up. SuperPay never holds funds or settles rewards.

Step 5 — Promote to production

Email hello@superpayrewards.com with your sandbox merchant ID and the production domain(s). We'll issue a live sp_live_ key and walk through your first 100 live transactions together.

One script tag. Your branding. Our reward affordance.

The SuperPay widget renders as a non-intrusive badge or button on your checkout. It's framework-agnostic — works inside Shopify themes, custom React/Vue checkouts, BigCommerce, WooCommerce, and bare HTML.

Customization options

Reference snippets

Node.js (Express) — server-side recommendation

import express from "express";
const app = express();

app.post("/cart/recommendation", async (req, res) => {
  const rec = await fetch("https://superpayrewards.com/v1/recommend", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.SUPERPAY_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      amount: req.body.subtotal,
      mcc: req.body.mcc,           // preferred
      category: req.body.category, // fallback
      merchant_name: req.body.merchantName,
    }),
  }).then(r => r.json());

  res.render("checkout", { recommendation: rec });
});

Python (Django/Flask) — server-side recommendation

import os, requests

def get_recommendation(subtotal, mcc, merchant_name):
    r = requests.post(
        "https://superpayrewards.com/v1/recommend",
        headers={
            "Authorization": f"Bearer {os.environ['SUPERPAY_KEY']}",
        },
        json={
            "amount": subtotal,
            "mcc": mcc,
            "merchant_name": merchant_name,
        },
        timeout=5,
    )
    r.raise_for_status()
    return r.json()

Shopify (Liquid theme) — drop-in widget

<!-- in your cart.liquid or checkout.liquid -->
<div data-superpay-recommend
  data-amount="{{ cart.total_price | divided_by: 100.0 }}"
  data-merchant="{{ shop.name }}"
  data-category="shopping"></div>
<script
  src="https://superpayrewards.com/v1/widget.js"
  data-key="{{ settings.superpay_api_key }}"
  async></script>

Free, forever.

The Card-Recommendation Widget is 100% free for merchants. No fees, no rev share, no contract minimums. SuperPay treats the widget as a value-add at checkout and a shopper-acquisition channel.

Questions about the API or want to discuss a custom integration? Email hello@superpayrewards.com.

What we do, what we don't

Need our security policy or to start a vendor review? View our security policy or email security@superpayrewards.com.

Common questions

Ready to ship?

Pre-launch checklist

• ☐ Sandbox key issued and successfully returning recommendations from /v1/recommend
• ☐ Widget rendering on your staging checkout
• ☐ Production domain(s) added to allowlist
• ☐ Cart amount + MCC (or category) wired into the widget mount on every checkout page
• ☐ Customer support team briefed on the affordance
• ☐ Live sp_live_ key issued and rotated into your env

Useful links

• /for-merchants — sign up & live widget demo
• /v1/docs — full API reference
• Download this guide as a PDF
• /blog — product & rewards strategy writing
• /security — security policy