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Guide · Security & privacy

How to redact a PDF properly

Reviewed

Hand holding a small brass padlock against a dark background

Short answer

To redact a PDF, use a redaction tool that deletes the content under each mark, not one that only draws a black box. Mark every occurrence of the sensitive text, apply redaction, then verify by searching for the redacted words and copying the area. A black rectangle drawn in an editor or a highlighter hides text visually but leaves it in the file, where anyone can copy it out.

On this page (7)

Why black boxes fail

A PDF page is built in layers. Drawing a rectangle adds a new shape on top of the text; the text itself is still there. Anyone can select the area and copy, search for the hidden words, or delete the rectangle in an editor. Published court filings and government reports have exposed names and figures this way.

The same applies to whiteout, highlighting in black, and covering text with an image. They change what you see, not what the file contains.

  1. 1Sensitive text

  2. 2Mark what to remove

  3. 3Removed from the file

What Redact PDF does, in three steps.

Redact a PDF in PDFBetter

  1. 1

    Open the PDF with Redact

    Upload the file; it opens in the editor with the redaction tool selected.

  2. 2

    Mark every occurrence

    Drag boxes over text, images or signatures. Use Search to find every place a name, account number or address appears, and mark each one.

  3. 3

    Review the marks

    Marks show as outlines until applied. Page through the whole document; anything not marked stays.

  4. 4

    Apply redaction

    Affected pages are rebuilt with the boxes burned in, so the content under them is gone. Annotations, form fields and metadata are stripped from the file.

  5. 5

    Download

    Downloading needs a free account. Your version history keeps the unredacted original for you; the redacted file does not contain it.

Verify the redaction

Open the downloaded file in a different PDF reader. Search for each redacted word or number; nothing should be found. Try selecting and copying across a redacted box and pasting into a text editor. PDFBetter also re-extracts the text after redaction to check the marked content is gone, but a check of your own takes a minute and catches marks you missed.

Hidden places sensitive data lives

Document properties (author, title, subject), comments and sticky notes, form field values, bookmarks, attachments embedded in the PDF and earlier versions saved inside the file can all carry information you redacted from the page. Redaction in PDFBetter strips annotations, fields and metadata, but doesn't inspect embedded attachments; remove those before sharing.

Trade-offs of true redaction

Pages that contain a redaction are rebuilt as images, so their remaining text is no longer selectable or searchable. Run OCR afterwards if you need that. The redacted file is also no longer fillable. Keep a private unredacted original in case you need to produce a different redacted version later.

Tools used in this guide

Questions people ask

Is redaction reversible?

Not in the redacted file. The content under each box is deleted. Your account's version history keeps your unredacted original privately.

Can I redact a scanned PDF?

Yes. Draw boxes over the areas to remove; the page image is rebuilt without them. Search only finds text in scans after OCR, so mark by eye or run OCR first.

Is the black box mandatory?

The removed area is shown as a solid box so readers know something was withheld. You can add a label, such as an exemption code, on the box.

What's the difference between erase and redact?

Erase paints over content and leaves it in the file. Redact removes it. Use erase for cosmetic fixes only.

Does PDFBetter find sensitive data automatically?

Search finds each occurrence of text you type, and you mark them. There is no automatic detection of personal data, so review the whole document.