pdfmasker

With this library you can mask sensitive text in PDFs or basically change any text in your PDF files.

Usage

from pdfmasker import mask_pdf

pdf_bytes = open("paystub.pdf", "rb").read()

result = mask_pdf(pdf_bytes, patterns=["Jane Doe", "123-45-6789"])

result.pdf       # bytes — the masked PDF
result.counts    # {"Jane Doe": 2, "123-45-6789": 1}

mask_with controls the replacement string; omit it (or pass None) to use the default mask (a run of X matching each target's length):

mask_pdf(pdf_bytes, patterns=["Jane Doe"], mask_with="[REDACTED]")

Masking backends

Text replacement is available through two independent implementations. mask_pdf uses the first one by default; the second is opt-in.

• Bundled binary (default). mask_pdf and Masker() drive a compiled Go engine over a subprocess. It works out of the box with the installed wheel and needs no extra dependencies.

• In-process (pikepdf). PikepdfTextLayerStrategy edits the PDF's content streams directly in Python, avoiding the per-call subprocess overhead. It is an optional dependency:

  pip install pdfmasker[pikepdf]
  

  from pdfmasker import Masker
  from pdfmasker.strategies.pikepdf import PikepdfTextLayerStrategy
  
  masker = Masker(strategies=[PikepdfTextLayerStrategy()])
  result = masker.mask(pdf_bytes, patterns=["Jane Doe"])
  

Both accept the same patterns and mask_with, and return the same MaskResult. The bundled binary is the more battle-tested path; the pikepdf backend trades that maturity for lower latency and a pure-Python dependency. Without the pikepdf extra installed, using the in-process strategy raises pdfmasker.MissingDependencyError.

Contributing

The architecture, repository layout, setup, dev commands (make help), the build/cross-build model, and the release flow all live in CONTRIBUTING.md.