I need to recommend a way for our partners to easily redact sensitive information from PDFs. I hope to find a free solution, because it is hard enough to get them to redact as it is, and it would be even harder if they have to purchase expensive software to do it.

Adobe Acrobat has a tool for redacting info from a PDF. The "Redact" tool lets you draw a rectangle over sensitive info, and the software destroys the underlying information for the text you covered up so it can't be recovered. There's no way for anyone to delete the rectangle and see what's underneath it; that information is permanently gone. This is the best way to do it, but I don't think I will be able to convince our partners to purchase Adobe Acrobat.

Is there any free software that can redact information from a PDF, with an interface that consists of simply drawing a rectangle over what you want to redact? Note that the software itself must do more than just draw a rectangle; it must actually irreversibly redact whatever is under the rectangle.

I posted about a multi-step process for doing this on security.se, using a combination of a few programs, but I am looking for a single program with a one-step process in this question.

The redaction should not affect the other data in the PDF. Printing to a TIFF or to paper, redacting, and then scanning or converting back into a PDF turns the entire document into an image, requiring OCR to get the text back and resulting in a loss of data.

An option to strip metadata would be a bonus.

Kind of related to Need program to help remove information from scanned documents, but these are computer-generated PDFs, such as those output by Word, not images. Converting to an image results in too much loss of data.

  • @Izzy Gratis, not libre. On Windows. Kind of leery about using a web app.
    – browly
    Jul 19, 2016 at 20:22
  • It may sound harsh, but with anything privacy/security oriented, it is your decision on how much it is worth to you. If the tool you need is not worth its price for you, then don't ask for what you would use that tool for. For serious redacting, the industry standard is Redax by Appligent, either as a server, or as a plug-in for Acrobat (which is the second best tool for redacting…).
    – Max Wyss
    Jul 21, 2016 at 0:47
  • @Max The problem is trying to get our partners to use it. Could our company purchase Redax and make it available to our partners through a web service or something so they can redact for free?
    – browly
    Jul 21, 2016 at 19:07
  • Talk to Appligent about possibilities. They are good people, and they may come up with something. And, again, damage caused by improperly redacted text can be magnitudes of the cost of suitable tools. But then, it is up to them to live dangerously.
    – Max Wyss
    Jul 22, 2016 at 5:09
  • @MaxWyss I've been trying to find more info about Redax, and you seem to be the only one on StackExchange who ever mentions it. Why do you say it is the "industry standard"?
    – browly
    Sep 12, 2017 at 16:13

2 Answers 2


The tools for redacting PDF can be expensive. But handing improperly redacted evidence to opposing counsel can be more expensive by orders of magnitude. Don't try to do this with free tools. Don't try to do this with cheaper tools. Blacking out a rectangular area of text is simple, but removing all content below it, through layers, overlapping text, black on black text, white on white text, is non-trivial.

Follow Max's advice and use either Acrobat Pro or Acrobat Standard with Redax.


I am surprised that I was not able to find anywhere the solution that eventually worked for me:

Why is it a good solution (at least for some cases)?

  • It is free
  • It is open source
  • It is cross-platform
  • It is secure (you are not uploading the original sensitive document anywhere) >> this is a very important point that is often neglected
  • The redacted data cannot be recovered: when you import the pdf, GIMP automatically converts it to an image, meaning that when you redact the sensitive data and export it as a pdf, it cannot be recovered in the source code of the pdf


  • Since it is converted to an image, you lose some quality and the final document does not have text
  • You can only import one page at a time

If there are any additional limitations, I would be happy to learn about them in the comments :)

How to redact data with GIMP

  1. Import the pdf file (this will automatically convert the PDF into an image)
  2. Select the area you want to redact
  3. Go to Filter > Blur > Pixelate (this is my preferred way, but you can hide the information in many other ways, including just a black box)
  4. Export

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