Send an invoice

Sends an invoice to the customer via the specified channel (email, SMS, or WhatsApp). A draft is approved first; a finalized invoice becomes sent. The send is refused, and nothing changes, when the invoice has no customer, the customer has no address for the channel, or nothing is due.

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Related endpoints

• GET /invoices/{id}/usage-explain — Explain invoice usage charges
• GET /invoices — List invoices
• POST /invoices — Create invoice
• GET /invoices/{id} — Get invoice
• PATCH /invoices/{id} — Update invoice
• GET /invoices/{id}/pdf — Get invoice PDF link
• POST /invoices/{id}/finalize — Finalize an invoice
• POST /invoices/{id}/void — Void an invoice

Common errors

• 400 invalid_request — malformed payload or failed validation.
• 404 resource_missing — the referenced resource does not exist or is not visible to your key.
• 409 conflict — Idempotency-Key collision with a different body, or a concurrent state-transition conflict.

Idempotency

Pass an Idempotency-Key header (UUID v4 recommended) to make retries safe. Keys are valid for 24 hours; see the idempotency guide.

Path Parameters

Send options

Response Body

curl -X POST "https://api.revkeen.com/v2/invoices/11111111-1111-4111-8111-111111111111/send" \
  -H "x-api-key: $REVKEEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "email",
    "template_id": "11111111-1111-4111-8111-111111111111"
  }'

{  "data": {    "id": "f1a2b3c4-d5e6-4270-8a9b-0c1d2e3f4a21",    "customer_uuid": "c2a1e7d4-5b3f-4a8e-9d21-6f0b3e4c7a11",    "invoice_number": "INV-0042",    "total_minor": 5880,    "currency": "GBP",    "allowed_methods": [      "card"    ],    "status": "paid",    "due_date": "2026-04-16T10:00:00.000Z",    "external_source": null,    "external_type": null,    "external_id": null,    "hosted_invoice_url": "https://pay.revkeen.com/inv_example_0042",    "created_at": "2026-04-16T10:00:00.000Z",    "updated_at": "2026-04-16T10:02:00.000Z"  },  "requestId": "req_7f3a9c2e5b1d"}