billing-engine

Open-source alternative to Stripe Billing and Lago for AI products: price tokens by model, sell prepaid credits, see margin per customer. Self-hosted; Stripe only charges the card (and works out tax, if you turn on Stripe Tax).

The Autonomous Revenue OS for Enterprise SaaS. Built with Next.js 15, PostgreSQL, Redis, and AI-driven growth agents.

Serverless utility rate engine on AWS: author bill calculations in a spreadsheet-like language (RDL) that transpiles to compiled Rust Lambda. React UI for rate authoring, plus batch processing for rate-case modeling across millions of bills.

Advanced billing engine for Laravel: subscriptions, proration, usage metering, addons, credit notes, and pluggable invoice/tax drivers on PostgreSQL. Built for SaaS, IaaS, and usage-based products.

A guide on how to sell your Plug-Ins to marketplace owners using Stripe

An enterprise-grade B2B SaaS subscription and customer management system featuring a state-driven billing engine, real-time metrics dashboards, and advanced filtering. Built as a high-performance monorepo with Java 25 / Spring Boot 4 and React 19 / Vite 8

Event-driven idempotent usage-based billing engine (POC v0.1). Ingest → idempotent process → versioned rating → aggregate → query → reconcile → MCP. Runnable locally (Docker; Kafka + Flink streaming tier), 100% line and branch coverage.

Real-time usage aggregation and rating engine for consumption-based cloud billing models.

RevRecover : AI-Assisted Revenue Recovery & Billing Compliance Control Plane

Agentic 3-way matching billing discrepancy engine detecting discrepancies across Purchase Orders, Quotes, and Invoices.

Monorepo for a B2B Micro-Suite: asynchronous billing core with NestJS, BullMQ, and Prisma, plus future RevOps modules. Built with pnpm workspaces as a modular monolith.

Agent-Orchestrated Multi-Tenant EAV Database Architecture for Dynamic Subscription Management

Production-grade usage metering, quota enforcement, and billing engine built with FastAPI, PostgreSQL, and Stripe. Features exactly-once idempotency, micro-cent integer money math, and signature-verified webhook synchronization. FlyRank AI Engineering Capstone.

An object-oriented C# subscription & billing engine with automated grace period handling and dynamic discount calculations.