Lago Billing - Open-source alternative to Stripe Billing and Chargebee

Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.

Metronome - Metronome helps software companies launch, iterate, and scale their usage-based business models, with billing infrastructure that works at any size and stage.

Chargify - Chargify is the best online billing software for all of your Recurring Billing needs. Learn more about simplifying your Subscription Billing today.

Recurly - Subscription billing and recurring billing management. Recurly offers enterprise-class subscription billing for thousands of companies worldwide.

Stripe Billing - A set of tools for billing and subscriptions