Financial infrastructure
Exactly-once settlement at financial scale
An event-driven microservices platform for high-value settlement, where a duplicated or dropped message is a financial loss rather than a retry.
- faster end-to-end settlement
- 0
- reconciliation breaks attributable to the messaging layer
- Exactly-once
- delivery semantics across service boundaries
The platform moved high-value settlements between counterparties. The existing design treated messaging as transport: publish, hope, reconcile later. The reconciliation team absorbed the cost every morning.
The problem
Settlement latency was the symptom. The cause was that transactional consistency stopped at each service boundary. A transfer could be committed locally and lost in transit, or applied twice. Nothing in the architecture made either impossible. They were only unlikely, until load rose.
What we built
An event-driven architecture where the log is the source of truth:
- Transactional outbox in each bounded context, so a state change and its event commit or fail together.
- Idempotent consumers keyed on a deterministic settlement identifier, so redelivery is a no-op instead of a double-spend.
- Bounded contexts drawn around money movement, not the org chart. The boundaries follow where consistency is required.
Result
End-to-end settlement time fell 40%. The bug where money moves twice was designed out instead of monitored for.