Why it matters
A usage number can affect both customer trust and invoices. Count the event at a clear boundary and define how retries, reversals and late data change the total.
Usage data may drive both customer trust and invoices. An event stream that is good enough for a graph may not be good enough to charge money from.
Decisions to make
- Choose billable units and the event that produces each unit.
- Define the period, timezone and aggregation rule.
- Decide how customers can inspect and dispute usage.
- Define the billable event and its unit precisely.
- Choose how corrections and delayed events affect a closed billing period.
Build checklist
- Write immutable usage events with idempotency keys.
- Reconcile aggregates against raw events.
- Test duplicate delivery, refunds and period boundaries.
- Deduplicate usage events with a stable identifier.
- Reconcile raw usage, aggregates and invoices for a sample customer.
Common mistakes
- Using an approximate dashboard counter as the billing source of truth.
- Counting API retries as new billable work.
- Changing a meter definition without versioning historical reports.
Tools & references
4 starting points to compare or study. Check fit, maintenance, terms and current capabilities before choosing one.
