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missing_parameter

HTTP Status: 400 Bad Request

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Example response

{
  "error": {
    "code": "missing_parameter",
    "message": "Query parameter 'vat_number' is required",
    "docs_url": "https://docs.vatly.dev/errors/missing_parameter"
  },
  "meta": {
    "request_id": "550e8400-e29b-41d4-a716-446655440000"
  }
}

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What happened?

The request to /v1/validate was missing the required vat_number query parameter. This happens when:
  • The vat_number parameter is completely absent from the URL
  • The parameter name is misspelled (e.g., vatNumber instead of vat_number)
  • The request body was sent instead of query parameters

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How to fix

  1. Add the vat_number query parameter to your request URL
  2. Make sure you’re using snake_case: vat_number, not vatNumber or vatnumber
  3. Pass VAT numbers as query parameters, not in the request body
# Correct
curl -H "Authorization: Bearer vtly_live_your_api_key" \
  "https://api.vatly.dev/v1/validate?vat_number=NL123456789B01"

# Wrong - missing parameter
curl -H "Authorization: Bearer vtly_live_your_api_key" \
  "https://api.vatly.dev/v1/validate"

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Common mistakes

  • Using vatNumber or vat-number instead of vat_number
  • Sending a POST request with a JSON body instead of a GET with query params
  • URL-encoding the ? character, preventing the parameter from being parsed