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How to redact a PDF properly

Redaction has one failure mode, and it is expensive: a black rectangle that looks convincing while the name, account number or address underneath can still be selected and copied. Several well-known leaks happened exactly that way. This guide covers redacting a PDF so the content is actually removed, and checking the file before it leaves your hands.

Updated September 15, 20266 min read

Do it nowRedact PDF
On this page
  1. 01Why drawing a black box is not redaction
  2. 02How to redact a PDF, step by step
  3. 03Check where information hides
  4. 04Keep the document off other servers

Why drawing a black box is not redaction

In a normal PDF editor, a black rectangle is just another object placed on top of the page. The text beneath it is still in the file: select the area, copy, paste, and it is all there. Real redaction removes the content from the document itself.

Redact PDF does this by turning each redacted page into pixels, so there is nothing left underneath the box to read.

How to redact a PDF, step by step

Redact before sharing, not after: once a file has gone out, redacting your own copy changes nothing.

  1. Open Redact PDF and add the document.
  2. Draw black boxes over everything that has to go.
  3. Run the tool and download the redacted file.
  4. Open Check a redaction, add the redacted file, and type the words that were supposed to be removed.

Because a redacted page becomes an image, its remaining text is no longer selectable. If the document must stay searchable, run OCR PDF on the redacted file afterwards — the removed words are gone and cannot come back.

Check where information hides

A redaction can succeed on the page and still leak. Check a redaction searches for the words you removed in the page text and in the places people forget: document properties and XMP metadata, comments and stamps, unflattened form field values, bookmark titles and the names of attached files. It folds case and accents, so a name typed in capitals is still found.

  • If the report finds nothing, the removal held.
  • If it finds something, it tells you where, so you can fix it before the recipient finds it.
  • Remove metadata clears author, producer and timestamps that a document carries invisibly.

Keep the document off other servers

Sending a document somewhere to have its secrets removed defeats the purpose. With DocuGrip the redaction and the check both run without the file being transmitted.

Do it now

Frequently asked questions

Yes. The redacted page is turned into pixels, so the covered text is no longer in the file. Run Check a redaction to confirm nothing remains elsewhere.

The page became an image so that nothing survives under the boxes. Run OCR PDF afterwards if you need the remaining words to be searchable.

Not in the redacted file — that is the point. Keep your original, unredacted file somewhere safe.

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