# Invoice Validation API (Strale)

> Invoice Validation API (Strale) is a paid API for AI agents from api.strale.io, paid per call via x402, $0.0216/call, status unknown (last checked 2026-09-14).

Validates invoice data including VAT number formats, line item arithmetic, tax calculations, and EU compliance requirements.

## Facts

- Endpoint: POST https://api.strale.io/x402/invoice-validate
- Price: $0.0216/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-strale-io-b5250a2e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_A80yZszZsHEEiK3iCYXBR

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability api-strale-io-b5250a2e -d '<json body>'
```

Example prompt: Can you validate this invoice for me? It has vendor VAT DE123456789, buyer VAT FR98765432100, a few line items totaling €1,240 plus 20% VAT — I need to make sure the math checks out and it meets EU compliance requirements.

## When to prefer this

Choose this endpoint when you need to programmatically validate invoice data for correctness and EU compliance before submission or payment — especially when dealing with cross-border EU VAT, multiple line items, or complex tax calculations that must be audited automatically.

## Known failure modes

- Missing or malformed invoice object returns 400 bad request
- Invalid JSON structure in invoice field causes parsing error
- VAT number format unrecognized for non-EU countries
- Empty line_items array may skip line item validation
- Service unavailable or payment failure returns 402 or 5xx

## How this service works

Validate invoice data: VAT number format, line item math, tax calculations, EU compliance requirements.

## Output

Returns a structured validation report indicating whether the invoice passes or fails, with specific errors or warnings for VAT number format issues, line item arithmetic mismatches, incorrect tax computations, and EU compliance violations.

## Example request

```json
{
 "invoice": {
  "total": 1488,
  "subtotal": 1240,
  "buyer_vat": "FR98765432100",
  "line_items": [
   {
    "quantity": 1,
    "tax_rate": 0.2,
    "unit_price": 1000,
    "description": "Software license"
   },
   {
    "quantity": 1,
    "tax_rate": 0.2,
    "unit_price": 240,
    "description": "Support services"
   }
  ],
  "tax_amount": 248,
  "vendor_vat": "DE123456789"
 }
}
```

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "invoice"
 ],
 "properties": {
  "invoice": {
   "type": "object",
   "description": "Invoice JSON with vendor_vat, buyer_vat, amounts, line_items"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "valid": {
  "type": "boolean"
 },
 "errors": {
  "type": "array"
 },
 "warnings": {
  "type": "array"
 },
 "eu_compliant": {
  "type": "boolean"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-strale-io-b5250a2e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.strale.io](https://www.zero.xyz/host/api.strale.io/llms.txt)