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PDFEngines supports watermark and stamp in three ways:
  • PDFEngines.watermark() for /forms/pdfengines/watermark.
  • PDFEngines.stamp() for /forms/pdfengines/stamp.
  • Optional watermark / stamp on PDFEngines.merge() and PDFEngines.split().
Watermark is rendered behind page content. Stamp is rendered on top of page content.

Dedicated routes

On these two dedicated routes, source and expression are required — the SDK asserts both are set before sending the request. downloadFrom, webhook, outputFilename, and trace are also accepted (see Request tracing); downloadFrom can fetch the watermark/stamp file itself remotely via field: "watermark" or field: "stamp".

Merge and split with overlays

Unlike the dedicated routes above, source/expression aren’t required when watermark/stamp are used as optional post-processing on merge() and split().

Watermark/stamp payload shape

Use PdfEngineWatermark and PdfEngineStamp:
For source: "image" or source: "pdf", set expression to the uploaded filename and provide the asset in file.