Event Sourcing
Complete audit trail for every operation. Reconstruct state at any point in time. Built-in snapshot support for fast recovery.
Plugin Architecture
Extend billing logic with discount hooks, tax calculators, lifecycle observers, and invoice generators. ISP-compliant — implement only what you need.
Multiple Billing Models
One-time purchases, subscriptions, and usage-based billing out of the box. Supports tiered pricing, volume discounts, and per-contract overrides.
Domain-Driven Design
Clean domain model with Contract, Invoice, Payment, and Usage aggregates. Clear boundaries, value objects, and repository interfaces.
Payment Gateway Abstraction
Pluggable payment gateway interface supporting charge, authorize/capture, refund, and payment method management. Stripe-style hierarchical fallback resolution.
Production Ready Patterns
Contract renewal with price promotion, payment-gated provisioning, credit ledger with FIFO consumption, and batch processing for large-scale operations.