Introduction
Get started with the Lucius Billing API for usage-based and subscription billing.
The Lucius Billing API powers the Contract-to-Cash (C2C) billing engine. It lets you programmatically submit usage events, query contracts and their pricing programs, and retrieve invoices with line items.
Who is this for?
If you have a Lucius contract with usage-based pricing, you'll use this API to report metered usage from your systems. Lucius rates each event against your pricing program, updates draft invoices in real time, and handles subscription charges automatically.
What can you do?
| Resource | Actions |
|---|---|
| Usage events | Submit metered usage (bulk), list events, get event by ID |
| Contracts | List your contracts, get contract details, view active pricing |
| Invoices | List invoices, get invoice detail with line items |
How it works
Your system submits usage → Lucius rates it → Invoice updated- Submit usage — POST events with a metric name, quantity, and timestamp
- Automatic rating — Each event is rated immediately against your contract's pricing rules
- Invoice projection — The matching draft invoice is updated with the new charge
- Billing cycle — At period end, invoices include both subscription and usage charges
Base URL
https://api.lucius.financeAll endpoints are under /v1/billing.
Next steps
- Quickstart — Submit your first usage event in 5 minutes
- Authentication — Set up your API key
- API Reference — Full endpoint documentation