php

CII for PHP: InvoiceXML API Examples

PHP code samples for creating, validating, and parsing CII electronic invoices using the InvoiceXML API. Compatible with PHP 7.0+ (PHP 8.x recommended), works in plain scripts, Laravel, Symfony, WordPress, WooCommerce, Drupal, Magento, or any other PHP framework. Zero Composer dependencies: uses PHP's built-in cURL extension.

For background on the CII syntax itself (what it is, when to use it standalone), see the main repository README.

Get your API key

Every example in this folder calls the InvoiceXML REST API. Sign up and generate a free API key here:

→ https://www.invoicexml.com/account/authentication

Pass it as a Bearer token on every request:

Authorization: Bearer YOUR_API_KEY

Important: set $apiKey in the examples to the raw key only, without the Bearer prefix. If your account page shows the full header value (e.g. Bearer ixml_a1b2c3...), copy only the part after Bearer . The code adds the prefix itself when building the Authorization header.

Requirements

• PHP 7.0 or later (PHP 8.2+ recommended)
• The cURL extension (php-curl), bundled with most PHP installations by default
• No Composer, no external libraries

These examples use the built-in curl_* functions and CURLFile (available since PHP 5.5), so they run on essentially any modern PHP install without composer install.

Files in this folder

File	Operation	API endpoint
create.php	Build a CII D16B XML invoice	POST /v1/create/cii
validate.php	Validate a CII file against the D16B XSD and EN 16931 rules	POST /v1/validate/cii
extract-json.php	Parse a CII XML into JSON	POST /v1/extract/json
ai-convert.php	(Experimental) Convert a plain PDF to CII with AI	POST /v1/transform/to/cii
render.php	Render CII XML into a human-readable PDF	POST /v1/render/cii/to/pdf

Each file is standalone and runnable with php create.php. Open the file, replace YOUR_API_KEY with your real key, and execute.

Note on the snippets below: they are excerpts from those files and assume $apiKey is already defined. When in doubt, copy the complete file.

---

Create a CII invoice in PHP

$payload = [
    'invoice' => [
        'invoiceNumber' => 'CII-2026-001',
        'issueDate'     => '2026-05-18',
        'currency'      => 'EUR',
        'seller' => [
            'name'              => 'Acme GmbH',
            'vatIdentifier'     => 'DE123456789',
            'legalRegistration' => ['identifier' => 'HRB 12345'],
            'postalAddress'     => ['line1' => 'Hauptstraße 12', 'city' => 'Berlin', 'postCode' => '10115', 'country' => 'DE'],
        ],
        'buyer' => [
            'name'          => 'Globex SAS',
            'postalAddress' => ['line1' => '15 rue de Rivoli', 'city' => 'Paris', 'postCode' => '75001', 'country' => 'FR'],
        ],
        'paymentDetails' => ['paymentAccountIdentifier' => 'DE89370400440532013000'],
        'lines' => [[
            'quantity'       => 10,
            'priceDetails'   => ['netPrice' => 150.00],
            'vatInformation' => ['rate' => 19.00],
            'item'           => ['name' => 'Senior consulting'],
        ]],
    ],
];

$ch = curl_init('https://api.invoicexml.com/v1/create/cii');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => json_encode($payload),
    CURLOPT_HTTPHEADER     => [
        'Content-Type: application/json',
        'Authorization: Bearer ' . $apiKey,
    ],
]);
$xml = curl_exec($ch);
file_put_contents('invoice-cii.xml', $xml);

Totals and the VAT breakdown are calculated from the line items when omitted, and the document declares urn:cen.eu:en16931:2017 in BT-24.

The response is the CII D16B XML document, validated against the EN 16931 rules before delivery.

Full example: create.php | API reference

---

Validate a CII file in PHP

$ch = curl_init('https://api.invoicexml.com/v1/validate/cii');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => [
        'file' => new CURLFile('invoice.xml', 'application/xml'),
    ],
    CURLOPT_HTTPHEADER     => ['Authorization: Bearer ' . $apiKey],
]);
$report = curl_exec($ch);
echo $report;

Returns a JSON validation report listing any rule failures (EN 16931 BR-* and BR-CO-* rules).

Full example: validate.php | API reference

---

Extract CII data as JSON in PHP

Useful for feeding CII invoices into REST APIs, ERPs, accounting systems, or any pipeline that prefers JSON over XML.

$ch = curl_init('https://api.invoicexml.com/v1/extract/json');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => ['file' => new CURLFile('invoice.xml', 'application/xml')],
    CURLOPT_HTTPHEADER     => ['Authorization: Bearer ' . $apiKey],
]);
$json = curl_exec($ch);
$data = json_decode($json, true);
// The invoice document sits under the "invoice" key of the response.
echo $data['invoice']['seller']['name'];

Full example: extract-json.php | API reference | Sample response

---

---

(Experimental) Convert a plain PDF to CII with AI

Experimental feature. Human verification required before any production use.

Real-world PDF invoices are often messy: scanned at low quality, irregularly formatted, multi-page, or missing fields that EN 16931 requires. AI extraction can make subtle mistakes that automated validators may not catch: wrong tax category codes, transposed amounts, missing seller VAT identifiers, incorrect currency formatting.

Always review the output before sending it to a customer or tax authority. See the AI conversion notes in the main README.

The endpoint takes the PDF alone; no extra parameters are needed.

$ch = curl_init('https://api.invoicexml.com/v1/transform/to/cii');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => [
        'file' => new CURLFile('plain-invoice.pdf', 'application/pdf'),
    ],
    CURLOPT_HTTPHEADER     => ['Authorization: Bearer ' . $apiKey],
]);
$xml = curl_exec($ch);
file_put_contents('converted-cii.xml', $xml);

Full example: ai-convert.php | API reference

---

Render CII as a readable PDF in PHP

CII is a machine format with no visual layer, so nobody can read it without tooling. This endpoint renders the XML into a formatted PDF preview, generated fresh from the structured data rather than extracted from any existing PDF layer, which makes it a quick way to eyeball what your XML actually says. The PDF is for reading only; the XML file remains the authoritative invoice for compliance and tax purposes.

$ch = curl_init('https://api.invoicexml.com/v1/render/cii/to/pdf');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => [
        'file'     => new CURLFile('invoice.xml', 'application/xml'),
        'language' => 'en',   // en, de, or fr
    ],
    CURLOPT_HTTPHEADER     => ['Authorization: Bearer ' . $apiKey],
]);
$pdf = curl_exec($ch);
file_put_contents('invoice-preview.pdf', $pdf);

Full example: render.php | API reference

---

Framework integration

Laravel

Return a CII invoice from a controller or route closure:

use Illuminate\Support\Facades\Route;

Route::get('/invoices/{id}/cii', function ($id) {
    $pdf = app(CIIService::class)->create($id);
    return response($pdf, 200, [
        'Content-Type'        => 'application/pdf',
        'Content-Disposition' => "attachment; filename=\"invoice-{$id}.pdf\"",
    ]);
});

Store the API key in config/services.php and read it via config('services.invoicexml.key').

Symfony

use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Annotation\Route;

class InvoiceController
{
    #[Route('/invoices/{id}/cii', name: 'cii_download')]
    public function download(int $id): Response
    {
        $pdf = $this->ciiService->create($id);
        return new Response($pdf, 200, [
            'Content-Type'        => 'application/pdf',
            'Content-Disposition' => "attachment; filename=\"invoice-{$id}.pdf\"",
        ]);
    }
}

WordPress and WooCommerce

Hook into WooCommerce order lifecycle events to generate CII invoices automatically:

add_action('woocommerce_order_status_completed', function ($order_id) {
    $order = wc_get_order($order_id);
    $pdf = create_cii_from_order($order);
    file_put_contents(WP_CONTENT_DIR . "/invoices/{$order_id}.pdf", $pdf);
});

The same pattern works in Magento, Drupal Commerce, and PrestaShop.

---

Common issues

• HTTP 401 Unauthorized: API key missing or invalid. Generate one at invoicexml.com/account/authentication and confirm you are sending Authorization: Bearer YOUR_API_KEY. A frequent cause: setting $apiKey to the whole Bearer xxx value, which sends Bearer Bearer xxx. Set the raw key only.
• HTTP 400 Bad Request on Create: a required field is missing or malformed. Frequent causes: IssueDate not in ISO format (YYYY-MM-DD), Currency not in ISO 4217 (EUR, USD), country codes not in ISO 3166-1 alpha-2 (DE, FR).
• Class "CURLFile" not found: PHP cURL extension is missing. Install with apt-get install php-curl (Debian/Ubuntu), yum install php-curl (RHEL), or enable the extension in php.ini.
• SSL certificate problem errors: the server's CA bundle is out of date. Update OpenSSL on the host, or set CURLOPT_CAINFO to a current cacert.pem from curl.se/ca/.
• Schematron BR-CO- failures on Validate*: line totals do not match the header total, or tax category and tax percentage are inconsistent. Recompute totals before posting.

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Resources

• Get an InvoiceXML API key
• Create CII API reference
• Validate CII API reference
• Extract JSON API reference
• Extract XML API reference
• Transform to CII API reference
• PHP cURL documentation
• Main repository README