B2B payments, limits & compliance for a fintech operator

A high-throughput B2B payments stack: counterparty limits and scoring, AML/KYC workflows, audit-grade ledgers and integrations with banks and payment providers.

Delivered functionality

Idempotent payment APIs, statuses, automated reconciliation with bank statements.

Counterparty/product limits; AML decision queues; compliance reporting; investigations, CSV/XML exports.

Keycloak roles and MFA.

Business outcomes

Dispute investigation time −40–55%; post-clearing workload ~−30% via idempotency + reconciliation.

Horizontal API scaling without maintenance windows.

Highlights
  • Ledger: double-entry, payment idempotency, daily batch reconciliation with the bank.
  • Limit policies and a risk engine with versioned rules and what-if simulation.
  • AML/KYC: investigation cases, checklists, external list integrations and scoring services.
  • Compliance-grade observability: tamper-evident audit logs, tracing, regulatory reporting exports.
Stack
Python 3.12 FastAPI PostgreSQL (ledger + partitions) Redis Apache Kafka Temporal.io (Saga / workflows) HashiCorp Vault Keycloak OpenTelemetry React + TypeScript pytest / contract tests
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