​
Architecture

The payment system is built on top of BetterAuth and provides:
  • Unified subscription management
  • Multiple payment provider support
  • Webhook handling
  • Subscription status tracking
  • Customer portal integration

​
Database Schema

The system uses a unified subscription model that supports both providers: 
model subscription {
  id                   String    @id
  provider             Provider  @default(STRIPE)
  plan                 String
  referenceId          String?
  stripeCustomerId     String?
  stripeSubscriptionId String?
  polarSubscriptionId  String?
  polarCustomerId      String?
  productId            String?
  status               String?
  seats                Int?
  periodStart          DateTime?
  periodEnd            DateTime?
  cancelAtPeriodEnd    Boolean?
  trialStart           DateTime?
  trialEnd             DateTime?
  metadata             Json?
  user                 User?     @relation(fields: [userId], references: [id])
  userId               String?
}

​
Available Payment Providers

​
1. Stripe

​
2. Polar.sh

​
Client-Side Integration

The payment system is integrated into the client using BetterAuth: 
import { createAuthClient } from "better-auth/react";
import { polarClient } from "@polar-sh/better-auth";
import { stripeClient } from "@better-auth/stripe/client";

export const authClient = createAuthClient({
  baseURL: process.env.NEXT_PUBLIC_SERVER_URL!,
  plugins: [
    polarClient(),
    stripeClient({
      subscription: true,
    }),
  ],
});

​
Server-Side Integration

The server-side implementation uses BetterAuth with both payment providers: 
import { betterAuth } from "better-auth";
import { polar } from "@polar-sh/better-auth";
import { stripe } from "@better-auth/stripe";

export const auth = betterAuth({
  plugins: [
    polar({
      client: polarClient,
      createCustomerOnSignUp: true,
      // ... polar configuration
    }),
    stripe({
      stripeClient,
      createCustomerOnSignUp: true,
      // ... stripe configuration
    }),
  ],
});

​
Subscription Management

The system provides a unified interface for managing subscriptions: polar.sh checkout 
// Get subscription status
const paymentDetails = await authClient.getPaymentDetails();
const isSubscribed = paymentDetails?.polar || paymentDetails?.stripe;

// Start checkout
await authClient.checkout({
  products: [productId],
  slug: productSlug,
});
stripe checkout 
// Get subscription status
const paymentDetails = await authClient.getPaymentDetails();
const isSubscribed = paymentDetails?.polar || paymentDetails?.stripe;

// Start checkout
await authClient.checkout({
  plan: productSlug,
});

​
UI Components

The boilerplate includes pre-built UI components for:
  • Subscription status display
  • Payment provider selection
  • Checkout flow
  • Customer portal access

​
Security Considerations

  1. Always use environment variables for sensitive data
  2. Implement proper webhook signature verification
  3. Use authenticated routes for subscription management
  4. Implement proper error handling for failed payments

​
Next Steps