Usage-based billing sounds simple until payment webhooks, partial refunds, and multi-tenant isolation collide. Metrics Billing Platform is the stack we extracted so others can fork instead of rediscovering the sharp edges.
Non-negotiables
- Idempotent event ingestion with explicit replay semantics
- Monthly invoice jobs that can be re-run without double-charging
- Razorpay reconciliation paths tuned for India-first flows
