SaaS Payment Integration: Stripe, Subscriptions & Billing Guide

Why Stripe

Stripe handles:

• Payment processing — Cards, Apple Pay, Google Pay
• Subscription management
• Security & compliance — PCI, fraud detection, 3D Secure

2.9% + 30 cents per transaction.

Pricing Models

• Flat Rate — One price, all features (like Basecamp $99/mo)
• Tiered — Starter/Pro/Enterprise (like Slack)
• Usage-Based — Pay per use (like Twilio)
• Freemium — Free tier + paid (like Notion)

Start flat for your MVP.

Implementing the Checkout Flow

Stripe Checkout (hosted, recommended) — 10-20 lines of code.

Stripe Elements (custom UI) — More code, more control.

The flow:

1. User clicks Subscribe
2. Create Checkout Session (server-side)
3. Redirect to Stripe
4. Payment processed
5. Redirect back to your app
6. Webhook confirms the payment

The Subscription Lifecycle

Trial → Active → Past Due → Canceled

Each state requires different handling in your application.

Webhooks Explained

Key events to handle:

• checkout.session.completed
• invoice.paid
• invoice.payment_failed
• customer.subscription.deleted

ALWAYS verify webhook signatures.

Handling Failed Payments

Dunning process:

• Day 0: Send email notification
• Day 3: Retry payment
• Day 7: Show in-app banner
• Day 14: Final notice / downgrade

Good dunning recovers 30-50% of failed payments.

Designing Your Pricing Page

• 2-3 plans max
• Highlight the recommended plan
• Show annual pricing with monthly option
• Scannable feature comparison
• Social proof
• FAQ section