KodyVOD

01The problem

A VOD access code carries real money, so every path that hands the same code out twice is a genuine loss. Orders arrive in waves around a release — and precisely when concurrent requests peak, the system must not give one code to two people.

02What I built

• A custom licensing engine issues a code in one indivisible operation — a code is either assigned to an order or free, never in between.
• Redis queues absorb the order peak and spread it over time instead of throwing it all at the database at once.
• Heavy side work is moved onto RabbitMQ so it never blocks the purchase path.
• Two payment gateways — Stripe and PayU — behind one shared interface, so an outage at one does not stop sales.

03What it does now

• One code reaches exactly one order, including under concurrent purchases.
• A sales peak does not turn into errors on the buyer's side.
• An outage at one payment gateway does not close the shop.