Kill Bill

Revenue infrastructure you own

Zuora, Chargebee and Stripe Billing are popular subscription management platforms. They are also systems that charge a percentage of your revenue as a platform fee, put your billing logic in someone else's database, and create a dependency that makes your pricing strategy and billing workflows someone else's infrastructure concern. Kill Bill is the open source billing platform used by businesses that need complete control over their revenue infrastructure: not just a hosted service with a constrained configuration model, but an actual billing engine they deploy and own. It handles subscription lifecycle management, usage-based billing, complex proration, automated invoicing, payment orchestration across multiple payment processors, revenue recognition and dunning, all without a per-transaction fee and without a vendor owning the logic that makes you money. Node deploys and manages Kill Bill as a production-grade managed service.

What Kill Bill is

Kill Bill is an open source subscription billing and payment platform, originally developed at Ning and now maintained by the Kill Bill core team. It is a Java-based billing engine designed for the complexity that real subscription businesses encounter: changing plans mid-cycle with correct proration, usage charges that vary by consumption within a billing period, trial periods with automatic conversion, free and discounted periods with correct accounting treatment, pauses and holds, dunning on payment failure, and the revenue recognition schedules that finance teams require for subscription revenues.

Kill Bill is not a simple invoicing tool with a subscription trigger. It is a billing engine with explicit models for subscription states, billing alignment, event-driven billing transitions, and pluggable payment processor integration. The same platform that handles a simple monthly flat-rate subscription also handles complex hybrid billing with fixed recurring fees, per-unit consumption charges, tier-based pricing, and add-on subscriptions, all on the same invoice, with correct proration and revenue recognition.

Kill Bill is used by SaaS businesses, telecoms operators, media platforms, marketplaces and any business whose revenue model is more complex than "charge a card £X on the first of the month."

Subscription lifecycle management

Kill Bill models subscription lifecycles with the precision that complex billing requires.

Plan catalogue: define your product plans with billing frequency, trial periods, fixed recurring fees, usage charges, add-on products and promotional pricing. The catalogue is the source of truth for what your products cost and how they bill. Changes to the catalogue apply prospectively without affecting existing subscribers on legacy plans.

Subscription states: subscriptions move through explicit states: trial, active, paused, cancelled, pending cancellation, and end-of-term. State transitions trigger billing actions correctly: a trial expiring generates the first paid invoice, a cancellation triggers proration of the final invoice, a pause stops billing until resume.

Plan changes with proration: customers upgrade, downgrade, change billing frequency and add or remove add-on products. Kill Bill calculates the correct proration for each change: the credit for unused time on the old plan, the charge for the new plan's remaining period. Billing is always mathematically correct regardless of when in the cycle the change occurs.

Trial periods: configure free trial periods of any duration with automatic conversion to paid at trial expiry. No-card trials that require payment details before conversion. Card-required trials that charge automatically unless cancelled before trial end. Kill Bill handles the lifecycle correctly in each case.

Add-ons and bundles: model subscriptions as base plans with optional add-ons that bill alongside the base. A customer's base SaaS subscription is billed monthly; additional user seats, storage overages and premium support are billed as add-ons on the same invoice. Add-ons are independent subscriptions linked to the base plan, each with their own lifecycle and billing rules.

Usage-based and consumption billing

For businesses with pricing that depends on what customers actually use, Kill Bill provides a usage billing engine that handles the complexity of metered charging.

Usage record ingestion: submit usage records to Kill Bill via API for any metric you want to charge for: API calls, data processed, active users, transactions, compute hours, seats used, bandwidth consumed. Kill Bill accumulates usage events over the billing period and calculates charges against the pricing rules in the plan catalogue.

Pricing models: charge a flat rate per unit, or apply tiered pricing where the rate per unit changes at defined thresholds (the first 1,000 API calls at £0.001 each, the next 9,000 at £0.0008, above 10,000 at £0.0005). Volume pricing where a single tier applies to the entire usage quantity. Block pricing where usage is purchased in bundles. Kill Bill supports all of these models without customisation.

Hybrid billing: combine fixed recurring charges with usage charges on the same invoice. A monthly platform fee plus usage charges for actual consumption, in a single invoice with clear line-item breakdown, is a standard Kill Bill billing pattern.

In-arrears and in-advance: usage charges can bill in arrears (at the end of the period, once the usage is known) or in advance (for pre-purchased usage credits). Kill Bill handles the accounting treatment for each correctly.

Real-time usage visibility: expose current-period usage to customers via API so they can see their consumption and projected charges before the invoice closes. Usage visibility reduces bill-shock disputes and supports customer self-service.

Payment orchestration

Kill Bill abstracts payment processing through a plugin architecture, allowing you to route payments through any payment processor without being locked into a single provider.

Payment plugins: Kill Bill's open source payment plugin ecosystem covers Stripe, Braintree, PayPal, GoCardless, Adyen, Worldpay, Square and dozens of others. Payments are processed through whichever gateway you have contracted with, through the Kill Bill API, without Kill Bill vendor-locking your payment processing.

Multi-gateway routing: route different payment methods to different gateways. Direct debit through GoCardless, cards through Stripe, enterprise customers through Adyen for enhanced fraud controls. Kill Bill handles the routing transparently; the billing logic is independent of the payment gateway.

Payment methods: store multiple payment methods per customer with a default method for automatic charging. Allow customers to update payment details without affecting their subscription state. Kill Bill handles tokenised card storage through the payment processor, so payment details never touch Kill Bill's database.

Retry and dunning: when a payment fails, Kill Bill's dunning system retries automatically on a configurable schedule, emails the customer, and can pause or cancel the subscription after a defined number of failures. Dunning logic is configurable per plan, with different retry schedules for different subscription types, different grace periods for enterprise customers, different escalation paths based on customer tier.

Invoicing and revenue recognition

Kill Bill generates invoices automatically from billing events and provides the accounting data that finance teams require.

Automatic invoice generation: invoices generate automatically at billing dates, incorporating all recurring charges, usage charges, prorations, credits and discounts applicable to the billing period. Each invoice is a complete, accurate financial document without manual intervention.

Credit and refund management: issue account credits that apply automatically against future invoices. Process refunds against completed payments. Kill Bill maintains the credit and refund records with correct accounting treatment.

Revenue recognition: for SaaS and subscription businesses with ASC 606 or IFRS 15 revenue recognition requirements, Kill Bill tracks deferred revenue schedules for each subscription. The recognised and deferred revenue position is available via API for export to your accounting system. Finance gets the data they need for compliant revenue recognition without manual spreadsheet calculations.

Invoice customisation: configure invoice templates with your branding, custom fields and specific line-item presentation. Invoices reflect your brand and contain the information your customers need, not a generic billing document.

Reporting and analytics

Kill Bill maintains a complete event store of every billing action, providing the raw data for any billing metric you need.

MRR and ARR tracking: monthly and annual recurring revenue by plan, by cohort, by acquisition period. Kill Bill's data model makes these calculations precise: upgrades add correctly, downgrades subtract correctly, churn is captured at the moment of cancellation.

Cohort analysis: group subscribers by acquisition period and track their retention and revenue over time. Identify which acquisition cohorts retain best and which plans have the highest lifetime value.

Churn analysis: track cancellations by plan, by customer segment, by tenure. Understand whether churn is voluntary or involuntary (payment failure). Calculate net revenue retention across the subscriber base.