E-Invoicing API: How to Integrate Peppol Into Your Software

If you build software that handles invoices, you need to support Peppol e-invoicing. The Belgian mandate requires it since January 2026, and the rest of the EU is following with ViDA by 2030. The good news: integrating Peppol does not require reading a 400-page XML specification. With the right API, you can send your first e-invoice in under an hour.

1. Why integrate e-invoicing via API?

Many businesses use the e-invoice.be dashboard to send and receive invoices manually. That works fine for low volumes. But if your software generates invoices (ERP, billing system, SaaS platform, marketplace), you want to automate this completely.

2. How Peppol works under the hood

Before integrating, it helps to understand the basics. Peppol is a network of Access Points that exchange structured documents. It works similar to email: you send through your Access Point, and it gets delivered to the recipient's Access Point.

The key point: you never need to touch UBL XML, worry about AS4 protocols, or manage SMP lookups. The API abstracts all of that away. You work with JSON.

3. What you need to get started

4. Sending an e-invoice via API

Sending an e-invoice takes two API calls. First, create the document. Then, send it.

Step 1: Create the invoice

POST https://api.e-invoice.be/api/documents/
Authorization: Bearer YOUR_API_KEY
Content-Type: application/json

{
  "document_type": "INVOICE",
  "invoice_id": "INV-2026-001",
  "invoice_date": "2026-02-17",
  "due_date": "2026-03-17",
  "vendor_name": "Your Company BV",
  "vendor_tax_id": "BE0123456789",
  "vendor_address": "Kerkstraat 1, 1000 Brussels, BE",
  "customer_name": "Client NV",
  "customer_tax_id": "BE0987654321",
  "customer_peppol_id": "0208:0987654321",
  "currency": "EUR",
  "items": [
    {
      "description": "Consulting services",
      "quantity": 10,
      "unit_price": 150.00,
      "tax_rate": 21.00
    }
  ]
}

Step 2: Send via Peppol

POST https://api.e-invoice.be/api/documents/{id}/send
Authorization: Bearer YOUR_API_KEY

// Response: the full document with updated state
{
  "id": "doc-abc123",
  "state": "SENT",
  "document_type": "INVOICE",
  "invoice_id": "INV-2026-001",
  "invoice_date": "2026-02-17",
  "vendor_name": "Your Company BV",
  "customer_name": "Client NV",
  "items": [...],
  "created_at": "2026-02-17T10:30:00Z"
}

That is it. The API converts your JSON to a valid UBL document, validates it, looks up the recipient on the Peppol network, and delivers it. The response returns the full document with the state updated to SENT.

5. Receiving e-invoices via webhooks

When someone sends your company an e-invoice via Peppol, you want your system to know about it immediately. This is where webhooks come in.

Configure a webhook URL in your dashboard. Every time an e-invoice arrives, we POST the invoice data to your endpoint as JSON. Your system can then process it automatically: import into your ERP, trigger an approval workflow, or update your accounting records.

// Incoming webhook payload (event: DOCUMENT_RECEIVED)
{
  "id": "doc-xyz789",
  "state": "RECEIVED",
  "document_type": "INVOICE",
  "invoice_id": "SUPP-2026-042",
  "invoice_date": "2026-02-15",
  "due_date": "2026-03-15",
  "vendor_name": "Supplier BV",
  "vendor_tax_id": "BE0111222333",
  "customer_name": "Your Company NV",
  "customer_tax_id": "BE0123456789",
  "subtotal": 1500.00,
  "total_tax": 315.00,
  "invoice_total": 1815.00,
  "items": [...]
}

No polling needed. No manual downloads. Invoices flow from your suppliers into your system in real time. For a deeper look at automating your incoming invoice flow, see our guide on vendor invoice management.

6. Available SDKs

We provide official SDKs for five languages. Each SDK wraps the REST API with type-safe methods, automatic retries, and built-in error handling.

All SDKs include auto-retry with exponential backoff, auto-pagination, and rich error types. For detailed examples in each language, visit the SDK documentation pages.

7. Common integration use cases

8. Frequently asked questions