Executive Summary: How to engineer zero-loss payment reconciliation, idempotent webhook handling, and automatic refund fallbacks across Razorpay, Stripe, and Cashfree.

In enterprise SaaS platforms like **Vedant Billing** (https://vedantbilling.com) and **Solidrix Dine** (https://dine.solidrix.com), payment gateway reliability is critical for financial reconciliation. ### 1. Idempotent Webhook Processing 1. **Cryptographic Verification:** Validating HMAC SHA256 signatures before reading request payloads. 2. **Idempotency Keys:** Storing transaction event IDs in Redis with atomic locks to prevent duplicate order credit or double debit. 3. **Asynchronous Processing:** Enqueuing payment state transitions via background jobs to respond to webhooks within 200ms. ### 2. Automated Ledger Reconciliation Automated cron jobs run daily reconciliation matching gateway settlement logs against internal invoice databases.