Measure product usage and generate bills for subscriptions and usage-based plans.
100% free open-source (AGPLv3 / Apache-2.0). Unlimited billable events and customers when self-hosted.

Subscription billing automation, invoicing & dunning workflows
Find a free app for the parts of Chargebee you actually use.
Compare the free allowance and limitations on each app’s page. These are workflow alternatives, rather than identical copies.