Kestrel Pay
Business banking that moves at the speed of the people who run it.
- Client
- Kestrel Financial Ltd
- Year
- 2023
- Duration
- 8 months
- Team size
- 7 engineers
Interactive Demo
A hands-on mock of the product we built — click around.
Demo interface shown in English.
The challenge
Kestrel Financial held an e-money licence and an ambitious plan — a business account that opens in under ten minutes — but no engineering team, and a legacy core vendor quoting eighteen months and seven figures. The regulatory constraints were non-negotiable: PSD2 strong customer authentication, full audit trails, and reconciliation to the penny across Faster Payments, Bacs and the card schemes. The platform also had to survive payday-scale traffic spikes, when thousands of SMEs run payroll inside the same hour. Every architectural choice had to satisfy the FCA’s operational-resilience expectations while leaving room to iterate weekly, not quarterly. The client needed a partner who could own compliance-grade delivery end to end.
Our solution
We built an event-driven microservices platform on Kubernetes: a NestJS ledger service enforcing double-entry accounting in PostgreSQL, Kafka for payment orchestration, and isolated services for onboarding (KYC via Onfido), card issuing and Open Banking aggregation. Idempotent consumers and a saga pattern kept every movement of money exactly-once, while a WebSocket operations console gave Kestrel’s support team live visibility of each payment in flight. AWS environments are managed with Terraform, and every release passes automated penetration-test and reconciliation gates before it can reach production.
Results
Technology stack
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