// CASE STUDY

Fintech / Wealth Backend

A wealth platform that survived its own growth.

IndustryFintech · Wealth management
Year2024
Scope
  • Backend rebuild
  • Real-time ledger
  • Admin tooling
  • Audit & observability
// TENSION

A wealth platform shipped fast, then ran into the back wall of its own success. The ledger was correct but slow; the admin tools were a thin shell over the database; the audit story was a Slack channel. A new round of regulatory questions was coming, and so was a customer cohort five times the size of the current one. The platform could not be paused to be fixed.

// STRATEGIC MOVE

We rebuilt under live load — ledger first, surfaces second.

We treated the ledger as the centre of gravity and rebuilt outward. A real-time double-entry layer replaced the batch reconciler, fed by an event stream the operators could replay. The admin tools were rewritten against the same API the customer surface consumed, so every action a support agent took had a customer-visible audit trail. Observability was added before the migration cutover, not after — so when the cutover happened, the unknowns were already on a dashboard. The legacy path stayed online behind a feature flag for the duration; the cutover was a flag flip, not a rollback risk.

Double-entry ledger visualisation — abstract grid of transactional pairs

The ledger is the product. Everything else is a surface.

Event-stream architecture diagram
Operator admin shell, rebuilt against the same API as the customer surface
Cutover under live load · feature-flagged · zero data lossCutover under live load · feature-flagged · zero data loss
Observability dashboard with per-account latency and error budgets

Don't pause the system. Replace it underneath.

// OUTCOME

Reference architecture · rebuilt under live load

Zero
Customer-visible downtime across the cutover window
Double-entry
Ledger model with replayable event stream
End-to-end
Audit trail · every admin action traceable to a customer event
Flag-gated
Legacy path retained for the duration of the migration

Sometimes things fail.We plan for that.

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// CREDITS
  • Lead ArchitectMirko Vanzo
  • EngagementBackend rebuild · admin tooling · observability
  • Year2024
// STACK
  • TypeScript · Node
  • PostgreSQL · event sourcing
  • Kafka-style event stream
  • OpenTelemetry · Grafana · Loki
  • Feature-flagged cutover
// NEXTMulti-tenant B2B SaaSA reference architecture for multi-tenant B2B platforms.