Zentro Wallet
DiscontinuedA twenty-microservice fiat and crypto wallet platform — top-up, withdrawal, P2P transfer, scan-to-pay and a merchant marketplace, across web and mobile.
The largest system I have been responsible for: a wallet holding both fiat and crypto balances, moving money between users, and settling with merchants — around twenty services with web and mobile clients on top.
I owned the architecture and led the team of seven who built it, while staying hands-on in the code and in review.
The hard part was never any single feature. It was that every feature touches the same balance, and that balance has to stay correct under concurrency, partial failure and retry — while fiat and crypto settle on completely different terms, one reversible and scheduled, the other irreversible and at nobody's pace. Telling a user "this is your money" honestly across both is a modelling problem long before it is a UI one.
The product has since been discontinued. Employer work, so there is no repository, no screenshots, and nothing here about its internals.