Use cases
End-to-end use-case guides for sign-up IDs, medical and LOPIVI certificates, receipts, invoices to Excel, batches, human review and US documents.
These guides solve concrete problems end to end: which options to send, how to decide with the verdict, what to store
in your database and how to test it with a test key (ck_test_…) without spending credits.
If you haven't made your first call yet, start with the quickstart. If you're unsure whether to analyze, classify, use batches or the widget, see which endpoint to use.
Spain and Europe
ID in a sign-up form
A valid DNI, NIE or passport, belonging to the person signing up, with a minimum age.
Sport medical certificate
Fit for sport, signed, stamped and not too old.
Sexual offences certificate (LOPIVI)
For coaches and volunteers: no records and recent.
Reconcile bank-transfer receipts
Amount, beneficiary IBAN and registration reference.
Invoices to Excel
Extract header, lines and VAT and download an XLSX per invoice or per batch.
Bulk processing with batches
Up to 100 documents per batch, webhooks, retries and combined export.
Analyze without storing
Data minimisation (GDPR): no file and no results kept.
Human review
What to do with the review verdict: queue, reviewer and a new photo.
United States
The catalogue has 31 US-specific types (licenses with PDF417, Form I-9 documents, IRS forms, pay stubs, bank statements…). Start with US documents and continue with the guide for your case.
US documents
Catalogue types, PDF417 (AAMVA), I-9 lists and identifiers.
Driver's license
Driver's license (AAMVA, 21+).
Form I-9
Form I-9 documents (Lists A/B/C).
Contractors with W-9
Contractors with W-9.
Income verification
Income: paystubs and bank statements.
ACORD 25 certificates
Certificates of insurance (ACORD 25).
Proof of address
Proof of address (utility bills).
What each guide uses
| Guide | expect | Main checks |
|---|---|---|
| ID in sign-up | es_dni, es_nie, passport | not_expired, holder, min_age_years |
| Medical certificate | medical_certificate_sport | max_age_days, require_signature, require_stamp, holder |
| LOPIVI | es_sexual_offences_certificate | max_age_days, holder |
| Receipts | payment_receipt | expected_amount, expected_iban, expected_reference |
| Invoices | invoice | invoice_totals and nif_check_digit validations |
Available types and their fields are in the document catalogue and in
GET /v1/document-types. Every check is explained in
Checks.
Next steps
Test mode
How Constaia ck_test_ keys work, what each test file returns and how to write automated tests with Vitest, PHPUnit or pytest without spending credits.
ID in a sign-up form
Validate a DNI, NIE or passport in a sports registration (not expired, belonging to the registrant, minimum age) with the widget, Express or Laravel.