RubbishRouter — Zapper Payment Cloud Function

What this does

Calls the Zapper Business API (v2) server-side to create a payment invoice and return a deep-link that opens the Zapper app directly to the payment screen. Keeps your API keys off the browser entirely.

One-time setup (5 minutes)

1. Install Firebase CLI

npm install -g firebase-tools
firebase login

2. Place files

Copy this folder's contents into your Firebase project's functions/ folder. Your project ID is already set: rubbishrouter-688b2

3. Install dependencies

cd functions
npm install

4. Deploy

firebase deploy --only functions

5. Your Cloud Function URL will be:

https://us-central1-rubbishrouter-688b2.cloudfunctions.net/createZapperInvoice

This URL is already set in pay.html — no further changes needed.

How it works

1. pay.html calls this function with { amountCents: 1500, reference: "RR_..." }
2. Function calls POST https://api.zapper.com/business/api/v1/merchants/76032/sites/96013/invoices with Representation-Type: deeplink/zappercode/v2
3. Zapper returns a deep link: https://www.zapper.com/payWithZapper?qr=...
4. Function returns link to pay.html which redirects the user
5. On mobile → opens Zapper app to payment screen
6. On desktop → opens Zapper hosted payment page
7. After payment → Zapper redirects to success.html?reference=RR_...

Payment confirmation

Once a user pays, Zapper will POST to your webhook URL. Set this up at: https://mp.zapper.com → Integrations → Webhook Recommended URL: a second Cloud Function onZapperWebhook (can add later) For now, success.html activates the account optimistically on redirect.

Your credentials (already embedded in index.js)

• Merchant ID: 76032
• Site ID: 96013
• Merchant API Key: 6c48d74081e0421bb1afce2edc9b4dde
• Merchant Site API Key: 1b8ba011df7b45e09c107e35aa70710c