•The Ledger - Double-entry design, chart of accounts, sub-ledger boundaries, immutability and correction rules, multi-currency representation, precision and rounding policy, and how balances are derived or stored. You'll define how we handle authorisation holds, reversals, partial and incremental captures, refunds, FX revaluation and unreconciled positions, and you'll be able to explain and defend those choices to Finance, auditors and regulators.
•Money movement correctness - Idempotency, exactly-once outcomes on top of at-least-once messaging, clear state machines for every transaction type, and well-defined failure, retry, timeout and compensation paths. For every integration, the question "what happens if the partner succeeds and we fail?" should have a written answer that you own.
•Card issuing - Architecture for authorisation, clearing and settlement as a Mastercard Principal Member, including real-time authorisation on the scheme's critical path, stand-in processing, authorisation expiry, disputes and chargebacks, tokenisation for Apple Pay and Google Pay, virtual and physical card lifecycle, and the strict latency and availability targets that come with it.
•FX and multi-currency wallets - Rate sourcing, quoting and rate locking, spread and exposure management, in-app currency exchange across our wallet currencies, and pre-funding and liquidity models that keep customers' balances safe and available.
•Cross-border transfers - Corridor architecture, payout rail integrations (local real-time rails, bank transfers, SWIFT and partner networks), pre-funding and nostro design, and sanctions and AML screening built in as a core design constraint, not an afterthought.
•Reconciliation and settlement - We treat reconciliation as an architecture problem, not an operations task. You'll design systems where breaks are rare, spotted within minutes, and traceable to a clear cause, across multiple time zones, currencies and partners.
•Non-functional requirements - Latency, throughput, availability and cost as design targets with numbers attached. Clear, written decisions on where eventual consistency is acceptable and where it isn't. Recovery, replay and backfill as built-in capabilities.
•Standards and technical judgement - Engineering and coding standards, architecture reviews for significant changes, and architecture documentation that engineers actually build from. You'll write decision records that capture the reasoning and the options rejected, and keep them current.
•Partners and vendors - Technical evaluation and ongoing oversight of card processors, scheme connectivity, banking and settlement partners, FX liquidity providers, payout partners, KYC and screening vendors, and core infrastructure. You'll know their systems' failure modes as well as their own architects do.
•Growing technical leaders - You'll mentor tech leads and senior engineers from day one and lead mostly through influence. As the function matures, you'll build and lead a small architecture group.
