VaultPay is a fintech wallet microservice responsible for balances, peer-to-peer transfers, KYC, and transaction security - while delegating all authentication concerns to AuthShield.
A strict boundary defines the system: VaultPay has no users table, never stores passwords, and never issues tokens. User identity lives entirely in AuthShield, while VaultPay operates purely on business data using user UUID references.
To balance performance and security, the system uses a dual-mode JWT validation strategy - local validation for standard requests (zero latency), and synchronous AuthShield verification for sensitive operations like PIN changes and KYC actions.
All money movement is handled through atomic database transactions, ensuring that multi-step operations either fully succeed or fully roll back. The system also maintains a complete audit trail, ensuring every success or failure is captured reliably.
The project showcases system-level thinking across service boundaries - combining authentication delegation, distributed RBAC, Redis-backed security controls, and database-enforced consistency into a production-grade architecture.