Overview

Kill Bill is a programmable billing system for businesses building subscription and payment workflows around APIs. It suits teams that need control over billing logic and can take responsibility for operating the software. Its flexibility is the draw; self-hosting also brings ongoing infrastructure and upgrade work.

Founded in 2010, Kill Bill is open source and supports subscription and usage-based pricing, invoices, and payment integrations. Staff can use Kaui, its web-based back office, to configure price books and manage subscriptions and payments. That combination gives technical teams a billing foundation and an administrative interface, rather than a finished, fully managed service by default.

Key features

Subscription and usage billing

Kill Bill supports subscriptions, usage-based pricing, multi-currency billing, and proration controls. Dunning and tax automation are also included among its capabilities. Together, these address common recurring-revenue operations, but teams should expect to configure the platform around their own billing needs rather than assume a turnkey workflow.

Payment integrations

Plugins connect Kill Bill with payment gateways, issuing banks, and fraud tools. Named integrations include Stripe, Adyen, PayPal, Braintree, GoCardless, and Coinbase, alongside tax services Avalara and Vertex. The breadth is useful for teams selecting their own payment stack; it also makes the plugin-based architecture central to how the platform fits into a business.

Back office, security, and compliance

Kaui provides a browser-based interface for price books, subscriptions, and payments. Security controls described for the platform include encryption at rest and in transit, TLS communications, AES-256 encryption for stored data, audit logs, role-based access, and tenant isolation. The maker says these technical controls are intended to help enterprises meet SOC 2 and PCI-DSS requirements; they are not a substitute for an organization's own compliance work.

Pricing

Kill Bill's pricing model is freemium, with free and paid options. The available deployment choices suit different operating preferences, but pricing and infrastructure obligations vary substantially.

Self-Hosted Open Source: custom pricing is not given; the open-source core is self-hosted, with control over infrastructure and data. Community support is included. This is the fit for teams willing to operate and upgrade the system in exchange for deployment control.
Hosted Platform (ChaChing): custom pricing under a separate commercial model. It is fully managed while retaining the Kill Bill APIs and data model, making it the option for teams that want managed operations rather than running the stack themselves.
AWS Marketplace: approximately $40/mo, plus AWS infrastructure costs. It runs in the customer's AWS account, and the customer operates the stack. This offers a paid deployment route for AWS users, but it does not remove the administration burden of self-hosting.

Paid support tiers for customer-managed deployments are purchased separately. The free trial is available, though its duration and terms are not given. The AWS price should not be treated as the full hosting cost because AWS infrastructure is additional.

Platforms

Kill Bill supports API access and Linux, macOS, and Windows environments, as well as web and self-hosted deployment. Installation options include Docker and Tomcat; it can run on a computer or a Linux cloud server. This range leaves deployment choices open, but self-hosted customers must manage upgrades and infrastructure themselves.

Who it's for

Kill Bill is best suited to online businesses, startups, and growth-stage companies with technical teams that need customizable billing logic, payment integrations, and control over deployment. It is less suitable for organizations seeking a hands-off billing service without separately choosing the managed platform or taking on operational work.

Pros and cons

Pros: Open-source self-hosting gives teams control of infrastructure and data, while support for usage pricing, proration, multiple currencies, dunning, and tax automation covers a broad set of recurring-billing needs.
Pros: Plugin integrations span payment gateways and tax services, and Kaui gives staff a web back office for core billing administration.
Cons: Self-hosted teams must operate and upgrade Kill Bill; community support comes with the open-source option, while paid support costs extra.
Cons: The AWS Marketplace price excludes infrastructure costs, and the hosted platform uses a separate commercial model, so those routes require distinct cost planning.

Alternatives

For a narrower or differently packaged billing setup, consider these subscription billing software options, dunning management software options, or payment processing software options.

Airwallex Billing is worth comparing if you want invoicing and usage-based billing with a free invoicing plan and a per-successful-transaction usage plan.
Churnkey is a more focused choice for teams addressing churn and payment recovery through cancel flows, recovery tools, and metrics; its Starter plan is aimed at teams with less than $5k/mo churn volume.
Pabbly Subscriptions may suit smaller customer bases seeking a free entry plan capped at 50 customers, or a $14.00 USD per month Standard plan.
UniBee is another self-hosted and customizable option; its open-source plan is free and requires manual setup, with community support.
Lago is a free, self-hosted alternative with an AGPLv3-licensed open-source plan.
OpenBRM is a free alternative available on web, Windows, macOS, and Linux.
Flexprice may fit teams wanting a free plan with a 100k-events-per-month allowance and up to $100K in cumulative billing revenue, including subscription, usage-based, and hybrid pricing.
WooCommerce is a free, self-hosted option if your requirement is its core offering of unlimited products, orders, and APIs.

Verdict

Choose Kill Bill if your team needs a customizable billing platform, wants control over its payment integrations and deployment, and can maintain a self-hosted stack or budget for the managed platform. Its API-centered design and broad billing capabilities are compelling for technical teams; look elsewhere if you need simple, fully managed billing without operational responsibilities or a clear single pricing model.

	Baremetrics	Kill Bill
Free plan	No	Yes
Free trial	Yes	Yes
Paid from	$75/mo	Free
Open source	No	No
Platforms	api, Web	api, Linux, macOS, self-hosted, Web, Windows
Free plan	No	Yes
Paid from	75 /mo	40 /mo

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