Preview invoice calculations

POST https://app.speybooks.com/api/v1/invoices/preview

Calculates line totals, VAT, and invoice total without creating an invoice. Use this for real-time UI previews while the user is editing line items.

All amounts are in minor units (pence). The calculation is deterministic and stateless — no data is persisted.

This endpoint is stateless and idempotent. No authentication scope is required beyond a valid API key.

Body parameters

lines array<object> required

min items: 1 · max items: 100

Show child parameters

quantity integer required

min: 1

unitPrice integer required

vatRate integer required

min: 0 · max: 100

Response

200 Default Response

Show response fields

lines array<object>

Show child attributes

net integer

total integer

vat integer

subtotal integer

total integer

vatTotal integer

Request POST /v1/invoices/preview curl

curl -X POST https://api.speybooks.com/v1/invoices/preview \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "lines": [
      { "quantity": 1000, "unitPrice": 50000, "vatRate": 20 },
      { "quantity": 1000, "unitPrice": 25000, "vatRate": 20 }
    ]
  }'

Response 200

{
  "success": true,
  "data": {
    "lines": [
      {
        "net": 50000,
        "vat": 10000,
        "total": 60000
      },
      {
        "net": 25000,
        "vat": 5000,
        "total": 30000
      }
    ],
    "subtotal": 75000,
    "vatTotal": 15000,
    "total": 90000
  }
}