E-Invoice API

Compliant E-Invoices from HTML in One API Call

Generate Factur-X and ZUGFeRD hybrid PDFs with embedded CII XML — no Java, no XML tooling, just a REST request.

Part of the PolyDoc Platform

PolyDoc is a REST API that converts HTML to PDF and screenshots. E-invoicing is one of its compliance features: pass your invoice data as JSON alongside your HTML, and receive a standards-compliant hybrid PDF — ready for accounting systems across the EU.

What Is an E-Invoice?

An e-invoice is more than a PDF. It is a hybrid document combining human-readable layout with machine-readable structured data.

Hybrid PDF

The visual invoice PDF embeds a CII XML file (Cross-Industry Invoice) that accounting and ERP systems can process automatically — no OCR, no manual entry.

EU Mandate

The European standard EN 16931 defines the semantic data model. Germany (via ZUGFeRD) and France (via Factur-X) require compliant e-invoices for B2B and B2G transactions.

DesignYour invoice HTML

ConvertPolyDoc API

DeliverHybrid PDF + XML

Standards & Profiles

PolyDoc supports both major European e-invoice labeling conventions. Both produce equivalent hybrid invoices built on the same CII XML model.

Factur-X

Recommended for France and cross-border EU scenarios. Conforms to the Franco-German joint standard.

"standard": "facturx"

ZUGFeRD

Common in German domestic invoicing. Based on the same underlying EN 16931 data model.

"standard": "zugferd"

Compliance Profiles

Choose the level of detail embedded in the XML. EN 16931 is the recommended default for standard EU B2B invoicing.

Profile	Typical usage
`minimum`	Minimal payment information, no line-item detail.
`basicwl`	Basic payment data without line items.
`basic`	Line items included, no allowances or charges.
`en16931`Recommended	Standard EU B2B compliance profile.
`extended`	Additional fields for complex invoicing scenarios.

How It Works

Three steps from HTML to a compliant hybrid invoice.

1. Design your invoice

Write invoice HTML or use a PolyDoc template with Liquid variables for dynamic data.

2. Send one API request

POST your HTML source and structured invoice JSON data. PolyDoc generates the CII XML automatically.

3. Get your hybrid PDF

Receive a PDF/A-3b document with embedded XML — ready for accounting systems, archives, and regulatory compliance.

Example API Request

POST https://api.polydoc.tech/v1/pdf
Authorization: Bearer YOUR_API_KEY
Content-Type: application/json

{
  "source": "<html><body><h1>Invoice INV-<n>2026</n>-<n>042</n></h1>...</body></html>",
  "eInvoice": {
    "standard": "facturx",
    "profile": "en16931",
    "verify": true,
    "invoice": {
      "number": "INV-<n>2026</n>-<n>042</n>",
      "issueDate": "<n>2026</n>-<n>03</n>-<n>15</n>",
      "dueDate": "<n>2026</n>-<n>04</n>-<n>14</n>",
      "currencyCode": "EUR",
      "seller": {
        "name": "Acme GmbH",
        "address": {
          "line1": "Hauptstrasse <n>1</n>",
          "city": "Berlin",
          "postalCode": "<n>10115</n>",
          "countryCode": "DE"
        },
        "taxId": "DE123456789"
      },
      "buyer": {
        "name": "Customer SAS",
        "address": {
          "line1": "Rue du Parc <n>5</n>",
          "city": "Paris",
          "postalCode": "<n>75008</n>",
          "countryCode": "FR"
        },
        "taxId": "FR98765432100"
      },
      "lines": [
        {
          "description": "Consulting services (<n>8</n> h)",
          "quantity": 8,
          "unitCode": "HUR",
          "unitPrice": 150.00,
          "lineTotal": 1200.00,
          "vatRate": 19.0,
          "vatCategoryCode": "S"
        }
      ],
      "totalNetAmount": 1200.00,
      "totalTaxAmount": 228.00,
      "totalGrossAmount": 1428.00
    }
  }
}

Key Capabilities

Everything you need for compliant e-invoicing, handled server-side.

Automatic PDF/A-3b

Every e-invoice is automatically converted to the archival PDF/A-3b standard. No separate configuration needed.

VeraPDF Verification

Optionally validate PDF/A compliance with the industry-standard VeraPDF engine. Results returned in response headers.

5 Compliance Profiles

From minimum to extended — choose the right level of data granularity for your use case.

CII XML from JSON

Pass structured invoice data as JSON. PolyDoc generates the Cross-Industry Invoice XML automatically.

No Java or XML Required

No Mustang, no XSD schemas, no Java runtime on your side. Just HTTP and JSON.

Single API Call

One POST request handles HTML rendering, XML generation, PDF/A conversion, and XML embedding.

Invoice Integrations

Pair PolyDoc with your accounting or automation tool. These guides show how to generate branded, compliant invoice PDFs.