Fintech backend engineering that knows the failure modes.
Fintech backend work has failure modes most engineers haven't seen before — double-counted events, aggregation drift, billing systems that break at scale. We've built this infrastructure ourselves.
Idempotent event ingestion
Retries double-count. We build event stores with proper idempotency keys and deduplication logic that holds 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 a discrepancy.
Engineers placed in fintech roles are screened for domain familiarity: PCI-DSS awareness, audit trail infrastructure, idempotent event system design, and payments data pipeline patterns.
Built on real fintech infrastructure experience
Generic engineering agencies build this wrong the first time. Fintech billing infrastructure is notoriously hard to rebuild — 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.
A standing fintech-screened backend team embedded in your workflow. $14k–$28k/month.
See dedicated teams →Specific fintech infrastructure build — billing system, event pipeline, audit trail. Scoped upfront. $20k–$70k.
See project engagements →Ready to talk fintech infrastructure?
30 minutes. We'll tell you whether we're a fit before you commit to anything.