Preview invoice calculations

POSThttps://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.

Request lines use the create format: quantity and unitPrice as exact decimal strings, with unitPrice in pounds and both accepting fractional values. The response returns per-line net, vat, and total plus aggregate subtotal, vatTotal, and total, all as integers in pence. The calculation path is identical to create, so what you preview is what you get on submit. Deterministic and stateless; nothing is persisted.

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

Body parameters

linesarray<object>required

min items: 1 · max items: 100

Show child parameters

quantitystringrequired

pattern: ^(?!0+(\.0+)?$)\d+(\.\d+)?$

unitPricestringrequired

pattern: ^\d+(\.\d+)?$

vatRateintegerrequired

min: 0 · max: 100

Response

200Default Response

Show response fields

linesarray<object>

Show child attributes

netinteger

totalinteger

vatinteger

subtotalinteger

totalinteger

vatTotalinteger

RequestPOST/v1/invoices/previewcurl

curl -X POST https://api.speybooks.com/v1/invoices/preview \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "lines": [
      { "quantity": "1", "unitPrice": "1500", "vatRate": 20 },
      { "quantity": "2", "unitPrice": "100",  "vatRate": 20 }
    ]
  }'

Response200

{
  "success": true,
  "data": {
    "lines": [
      {
        "net": 150000,
        "vat": 30000,
        "total": 180000
      },
      {
        "net": 20000,
        "vat": 4000,
        "total": 24000
      }
    ],
    "subtotal": 170000,
    "vatTotal": 34000,
    "total": 204000
  }
}