Webhooks (legacy)
Legacy invoice webhooks (v0) were retired on 2026-06-30.
Legacy invoice webhooks (v0) were retired on 2026-06-30. They sent an unsigned POST when an invoice finalized.
Their replacement is usage alert webhooks (GA 2026-12-01): signed, retried,
and configured per alert. Until then, poll GET /v1/invoices/preview.
If you set up v0 webhooks through a partner, their setup guide explains how to remove the endpoint. HTTP semantics for webhook receivers follow RFC 9110.