Idempotency
A shop ledger page, 1899. Every line adds up.
LLD Series: Payment Gateway with Routing, Retries and Webhooks (Low-Level Design)
Design a payment gateway (Razorpay / PayU / Stripe style). Merchants submit payments by card, UPI, net-banking or wallet. The gateway routes to a bank/acquirer, falls back if one is down, retries...
29 min read
LLD Series: Digital Wallet (Low-Level Design)
Design a digital wallet (Paytm / PhonePe / PayPal style). Users can add money, transfer to other users, and view history. Make transfers safe under concurrent requests, idempotent on retries, and...
21 min read