💳 Payments

ExtensionFast uses Stripe for payments and Firebase for backend processing. This guide walks you through how to set up everything from scratch — no backend experience required.

🧾 What We’ll Set Up

• A Stripe product with at least one price to charge users
• A Firebase project with Firestore + Functions
• A Stripe webhook that talks to your Firebase backend
• A working system to know who paid and who hasn’t

🧪 Stripe Test Mode vs. Live Mode

Stripe provides both a Test Mode and a Live Mode.

• Test Mode: This allows you to simulate payments and webhook events without using real money. It’s crucial for development and testing your integration thoroughly. You’ll use separate test API keys and webhook secrets for this mode.
• Live Mode: This is when you’re ready to accept real payments from your users. You’ll switch to your live API keys and webhook secret.

It’s highly recommended to do all your initial setup and testing using Stripe’s Test Mode before switching to Live Mode. This will help you identify and fix any issues without affecting real customers.

You can toggle between Test and Live modes in your Stripe dashboard using the switch in the top left corner.

1. Stripe Setup

First, create a Stripe account at https://stripe.com .

Once you’re in:

2. Firebase Setup

Go to https://console.firebase.google.com  and create a new project.

Once your project is ready:

The extension used inside Firebase (Run Payments with Stripe) automatically creates and manages the following Firestore (Firebase database) paths:

• /products/{productId} Stores product information from Stripe. Used to list available products for users.

• /products/{productId}/prices/{priceId} Stores prices for each product. Required for setting up payments or subscriptions.

• /customers/{uid} Links a Firebase Auth user to a Stripe Customer. Central to managing user billing.

• /customers/{uid}/checkout_sessions/{sessionId} Used to create and track Stripe Checkout sessions. Triggers Stripe to create a checkout flow.

• /customers/{uid}/subscriptions/{subscriptionId} Stores subscription data for the user. Helps track active plans and billing status.

• /customers/{uid}/payments/{paymentIntentId} Logs one-time payments made by the user. Useful for purchase history and receipts.

After it’s done installing, Firebase will give you a Webhook URL — copy this!

3. Create the Webhook in Stripe

Now go back to Stripe to let it talk to your Firebase backend.

4. Add Webhook Secret to Firebase

Go back to Firebase:

5. Firestore Security Rules for “Run Payments with Stripe” Extension

To safely manage user and payment data, it’s important to limit access in Firestore. These rules help ensure that:

• Users can only read or write their own data.
• Sensitive Stripe customer data is protected.
• Product and pricing information is publicly accessible.

6. Add these rules to your Firestore rules:

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
 
    // Users collection (if you're managing user documents)
    match /users/{docId} {
      allow create: if request.auth != null && request.auth.uid == request.resource.data.uid;
      allow read, update, delete: if request.auth != null && request.auth.uid == resource.data.uid;
    }
 
    // Stripe customer data linked to Firebase users
    match /customers/{uid} {
      allow read: if request.auth.uid == uid;
 
      // Stripe checkout sessions
      match /checkout_sessions/{id} {
        allow read, write: if request.auth.uid == uid;
      }
 
      // Stripe subscriptions
      match /subscriptions/{id} {
        allow read: if request.auth.uid == uid;
      }
 
      // Stripe payments (one-time purchases)
      match /payments/{id} {
        allow read: if request.auth.uid == uid;
      }
    }
 
    // Public product catalog from Stripe
    match /products/{id} {
      allow read: if true;
 
      // Pricing options for each product
      match /prices/{id} {
        allow read: if true;
      }
 
      // Tax rate info if used
      match /tax_rates/{id} {
        allow read: if true;
      }
    }
  }
}

Checkout Session Redirects

When a payment is successful or unsuccessful after initiating the Stripe checkout session, the user will be redirected to a success/unsuccesful screen, these are already set for your convenience:

• Success - https://extensionfast.com/extension/success 
• Unsuccessful/Cancel - https://extensionfast.com/extension/cancel 

If you would like to change these redirect screens to your own website, there are variables inside info.ts where you can place your own links.

That’s it! You now have a full payment pipeline that:

• Lets users pay with Stripe
• Uses Firebase Functions to handle success/fail
• Stores one-time payment info in the Firestore
• Stores subscription payment info in the Firestore

✅ Recap Checklist

• Stripe account created
• Product added in Stripe
• Firebase project set up
• Firestore + Functions enabled
• Stripe extension installed in Firebase
• Webhook created in Stripe with Firebase URL

💬 Additional Resources

• Firestore documentation  – For more documentation from Firebase
• Stripe documentation  – For more documentation from Stripe