Design a Wallet Under Concurrent Debits · System Design Interview

Design a Wallet Under Concurrent DebitsDesign the balance behind a payment wallet, where several charges against the same account can arrive in the same millisecond and the balance may never go negative.What it has to do

A debit is refused when the balance cannot cover it

A retried request debits once, however many times it arrives

The balance always equals the sum of the movements behind it

Scale

Wallets: 200 million

Movements per day: 4 billion

Out of scope

Card networks and settlement

Currency conversion

Fraud scoring

Statements and reporting

Practise this challengeAll system design challenges

LetsDiscuss

Loading your session…