Merging documents

PdfDocumentMerger combines multiple PdfDocument objects into one.

Basic usage

use PhpPdf\Document\PdfDocumentMerger;

$docA = (new PdfDocumentBuilder())/* … */->build();
$docB = (new PdfDocumentBuilder())/* … */->build();

$merged = (new PdfDocumentMerger())
    ->add($docA)
    ->add($docB)
    ->build();

$output = new PdfMemoryOutput();
(new PdfDocumentSerializer($output))->writeDocument($merged);

Pages are added in the order the documents are passed to ->add().

How merging works

The merger copies each source document’s object graph (fonts, images, content streams, resource dictionaries) into a shared PdfObjectRegistry. Object numbers are reassigned to avoid collisions. The page tree is rebuilt from the merged page list.

Each page retains its own fonts and resources unchanged — a page using Times-Roman stays in Times-Roman regardless of what other pages use.

Limitations

For non-destructive combination of already-signed or encrypted PDFs, use page-by-page import via PdfDocumentEditor or template import instead.