Kill Bill is an open-source billing and payments platform for businesses that want control over their infrastructure, data, and costs. Its self-hosted core supports subscription billing, usage-based pricing, payment processing, and complex prepaid or postpaid models, with fixed-cost alternatives to fees based on a percentage of revenue. The platform is designed for startups and large enterprises across SaaS, AI, marketplaces, fintech, and other industries.

Products include subscription management, payment-provider integrations, usage metering, wallets and credits, pricing catalogs, tax and compliance tools, and plugins for connecting existing systems. Kaui provides a web-based administration interface for managing customers, subscriptions, payments, and pricing. Teams can deploy Kill Bill themselves using Docker or AWS, access its source code and community support, or choose Aviate, a managed offering with cloud infrastructure, monitoring, and operational tools for faster deployment. Kill Bill also provides documentation, API references, tutorials, and enterprise support options. With more than 15 years in production and claims of processing billions in revenue, the platform emphasizes scalability, extensibility, predictable pricing, and freedom from vendor lock-in.