How to Build a Subscription Billing App with Strapi 5, Stripe, and Polar

The tutorial provides a comprehensive guide for building a subscription billing application using Strapi 5 as a headless CMS, along with Stripe and Polar for payment processing and compliance, respectively. It addresses the complexity of managing subscription billing across multiple providers by modeling subscription plans in Strapi, integrating Stripe for direct payment processing, and using Polar for tax compliance and billing infrastructure. The guide details the creation of custom routes and controllers to manage checkout flows, verify webhook signatures, and maintain subscription state synchronization across systems. Strapi serves as the single source of truth for plan metadata, while Stripe and Polar provide complementary roles in the billing stack. The integration involves configuring API permissions, setting up payment provider accounts, and ensuring the correct handling of webhooks to update subscription records. The tutorial emphasizes the importance of idempotency in webhook processing and offers strategies for testing the full billing flow, including using test cards and webhook tunneling for local development. Overall, it presents a robust framework for establishing a scalable and efficient subscription billing system.