Lago

Lago is an open-source billing platform designed for usage-based and subscription billing. It helps companies manage invoices, metering, and revenue analytics. The platform replaces traditional systems like Stripe Billing or Chargebee with a developer-first approach. It handles complex pricing models, including tiered, volume-based, and flat fees.

Lago integrates with Stripe, Plaid, and other payment gateways. It supports real-time usage metering for events, alerts for spending limits, and automated dunning management. The platform is built with Ruby on Rails and uses PostgreSQL. You can use the hosted cloud version or self-host via Docker for full control.

Lago is ideal for startups and SaaS companies that need flexible billing logic. The open-source community edition is free under Apache 2.0, with paid enterprise features available. It was founded by the team behind the open-source project, which has been adopted by companies like GitBook and Jellyfish.