invoice

Invoice

Number, dates, seller and buyer tax IDs, lines, VAT and total, reconciled.

Category: Payments and finance
Country: International
Extracted fields: 10 fields
Cost: 1 credit

Constaia extracts the whole invoice, checks the tax IDs and that base, VAT and total add up. For non-standard invoices, pass your own JSON Schema in extract.

What it checks

NIF/NIE check letter. The check character is recomputed (mod 23).
Totals. Net amount, taxes and total add up.
Expected values. Amount, reference or IBAN match the ones you provide.

Extracted fields

Numbernumber
Issue dateissue_date
Seller (name, tax ID, address)seller
Buyerbuyer
Line itemslines
Tax basetax_base
VATvat
Withholdingwithholding
Totaltotal
Currencycurrency

Where it is used

Sample request

curl https://api.constaia.com/v1/analyze \
  -H "Authorization: Bearer $CONSTAIA_API_KEY" \
  -F "file=@document.pdf" \
  -F 'options={
    "expect": "invoice",
    "checks": {
      "require_fields": [
        "number",
        "total"
      ]
    },
    "storage": "none"
  }'

Sample response

Fictitious data. Shortened response.

200 OK · application/json

{
  "id": "an_01J9Z3K8QW4T6Y2B7N5M1R0PXC",
  "object": "analysis",
  "status": "completed",
  "livemode": false,
  "document": {
    "type": "invoice",
    "label": "Invoice",
    "confidence": 0.97
  },
  "verdict": {
    "expected": [
      "invoice"
    ],
    "match": true,
    "status": "valid",
    "reasons": [
      {
        "code": "type_match",
        "severity": "info",
        "message": "The document is: Invoice."
      }
    ]
  },
  "fields": {
    "number": {
      "value": "F-2026-0412",
      "confidence": 0.99,
      "validated": true
    },
    "issue_date": {
      "value": "2026-09-15",
      "confidence": 0.98,
      "validated": null
    },
    "tax_base": {
      "value": 100,
      "confidence": 0.97,
      "validated": null
    },
    "total": {
      "value": 121,
      "confidence": 0.96,
      "validated": null
    },
    "currency": {
      "value": "EUR",
      "confidence": 0.99,
      "validated": null
    }
  },
  "checks": [
    {
      "code": "tax_id_check_digit",
      "passed": true,
      "message": "The tax ID is correct."
    },
    {
      "code": "totals_balance",
      "passed": true,
      "message": "Base, VAT and total add up."
    }
  ],
  "warnings": [],
  "storage": {
    "mode": "none",
    "file_deleted_at": "2026-09-29T10:00:02Z",
    "expires_at": null
  },
  "usage": {
    "credits": 1,
    "pages": 1
  }
}

FAQ

Does Constaia prove the document is authentic?

No. It checks the type, data consistency and your rules, and flags signals such as a possible edit or a screen photo. That does not prove authenticity.

Is a copy of the document kept?

No, unless you ask for it. With storage "none" (the default) the file is deleted when the analysis ends.

And for the record…

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