What should I use to watermark and stamp PDFs in bulk?

For bulk PDF watermarking/stamping, the best tool depends on whether you want simple command-line automation, desktop batch processing, or enterprise-scale document workflows.

Good options

1) Adobe Acrobat Pro

• Best if you already use Adobe.
• Supports batch actions and applying stamps/watermarks to many PDFs.
• Good for non-developers, but can be expensive and less ideal for large automated jobs.

2) Python + PyMuPDF (fitz)

• Great for custom bulk processing.
• Fast, reliable, and can add text/image watermarks, stamps, page numbers, headers/footers.
• Ideal if you want to automate a folder of PDFs.
• Best choice if you’re comfortable with scripting.

3) pikepdf / QPDF / Ghostscript

• Useful for lower-level PDF manipulation.
• Ghostscript is strong for post-processing and can be very fast for batch jobs.
• Better for technical workflows, especially if you need automation on servers.

4) PDFtk / Sejda / Nitro / Foxit

• Easier GUI tools for batch stamping/watermarking.
• Good for office use, less flexible than scripting.

5) Apache PDFBox (Java)

• Solid for Java environments and server-side processing.
• Good if your stack is Java-based.

My recommendation

• Need manual but bulk GUI use: Adobe Acrobat Pro or Foxit/Nitro.
• Need repeatable automation: Python + PyMuPDF.
• Need server-side high-volume processing: Ghostscript, QPDF, or PDFBox depending on stack.

If you want, I can recommend the best tool for your exact use case based on:

• how many PDFs,
• whether you need text or image watermarks,
• and whether you want GUI or script-based automation.