Attachments

Attach files with attachments. They appear in the viewer's attachment panel:

const pdf = await render(invoice, {
  attachments: [
    {
      name: "factur-x.xml",
      data: xml,
      mimeType: "application/xml",
      description: "Factur-X invoice data",
      relationship: "alternative",
    },
  ],
});

data takes raw bytes as a Uint8Array, or a string encoded as UTF-8.

relationship states how the file relates to the document. It becomes the PDF/A-3 AFRelationship:

Electronic invoices

ZUGFeRD and Factur-X invoices are PDF/A-3 documents with the invoice XML attached. Combine attachments with pdfa:

const pdf = await render(invoice, {
  pdfa: "3b",
  metadata: { title: "Invoice 1042", creationDate: "2026-08-06" },
  attachments: [
    {
      name: "factur-x.xml",
      data: xml,
      mimeType: "application/xml",
      description: "Factur-X invoice data",
      relationship: "alternative",
    },
  ],
});

The PDF/A-3 levels require three fields on each attachment:

• mimeType
• description
• a modification date: modificationDate, or the metadata.creationDate fallback

A missing field fails the render with the violated rule.

Invalid combinations are TypeScript type errors. The PDF/A-2 levels and "4" forbid attachments. The PDF/A-3 levels require mimeType and description on each one.

Full Factur-X conformance also expects its XMP extension schema. Takumi does not write it yet.