Backend teams that speak fintech.
Fintech backend work has a failure mode most engineers haven't seen before. Double-counted events. Aggregation drift. Plan changes applied to closed invoices. We've built this infrastructure ourselves — we know the failure modes before you hit them.
Idempotent event ingestion
Retries double-count. We build event stores with proper idempotency keys and deduplication logic at scale.
Usage-based billing systems
Meter versioning, mid-period plan changes, backfill without breaking closed invoices. The infrastructure problems Stripe doesn't solve for you.
Payment processing backends
Webhook handling, reconciliation pipelines, multi-currency aggregation, ledger systems. Production-grade, not tutorial-grade.
Audit trail infrastructure
Immutable event logs, 6–7 year retention, queryable audit trails your support team can actually use to explain an invoice.
Why this matters for your team
Generic engineering agencies build this wrong the first time, and fintech billing infrastructure is notoriously hard to rebuild. The failure modes compound — a double-counting bug in your metering layer becomes an invoicing discrepancy becomes a support escalation becomes a churn risk.
Fulmenflux's founder built ABAXUS — a self-hosted billing engine that runs inside Kubernetes and solves the exact infrastructure problems listed above. Your team works with engineers who have shipped this, not engineers reading about it.
Ready to talk fintech infrastructure?
20 minutes. We'll tell you whether we're a fit before you commit to anything.