Event-sourced payment gateway with real-time ML fraud detection, double-entry ledger, and PCI DSS 4.0-aware security controls. Built with Rails 8, Next.js 16, and LightGBM.
Every component is built to the same standards you would find in a real payment processor — from cryptographic security to ML-powered fraud intelligence.
Full lifecycle management — authorize, capture, refund, void. Event-sourced state machine ensures every transition is auditable and deterministic.
LightGBM model trained on 200K+ synthetic transactions achieves AUC 1.0. SHAP explanations provide feature-level transparency for every risk score.
Every financial movement creates balanced debit/credit entries. Append-only design with database-level invariants ensures the books always balance.
AES-256-GCM encryption at rest, blind index search, JWT + MFA authentication, rate limiting, and PCI DSS 4.0-aware controls. Brakeman clean.
Rails Event Store captures every state change as an immutable event. CQRS separates read/write models. Saga orchestration manages complex workflows.
Real-time notifications with HMAC-SHA256 signatures, exponential backoff retry (5 attempts over 24h), and delivery tracking in the dashboard.
PayForge is structured as a modular monolith with domain-driven boundaries. Each domain — Payments, Ledger, Fraud, Merchants, Webhooks — is isolated with its own models, services, and policies, communicating through an internal event bus powered by Rails Event Store.
Built with modern, battle-tested technologies
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