Redact PDF

How the PDF Redactor works

Drawing a black rectangle over a name in a PDF editor hides it on screen, but the text is usually still in the file underneath. Anyone can select it, copy it, or search for it. Court filings, government reports and company documents have been published this way for years, with "redacted" names recovered by simply copying and pasting the black box. A real redaction removes the text itself, not just the view of it.

How to redact PDF files

1. Drop the PDF into the box.
2. Type each word, name, number or phrase to remove, separated by commas, for example Jane Smith, 07700 900123, Flat 4.
3. Pick a resolution and run the tool.
4. Check the preview and download the copy ending in -redacted.pdf.

Matching ignores capitals and treats any run of spaces as one, so jane smith also catches Jane Smith and JANE SMITH.

How it works

The text of each page is read with pdf.js, Mozilla's open-source PDF reader, and every match is located on the page. The page is then drawn as an image, solid black boxes are painted over each match, and the image becomes the new page in a fresh PDF built with pdf-lib.

That last step is what makes the removal permanent. The new file contains only pictures of the pages, so there is no text layer, no hidden objects under the boxes, no earlier revisions, no form fields, no comments, no attachments and no document metadata such as the author's name. Whatever was under a black box no longer exists in the file in any form.

Choosing a resolution

Each page becomes an image, so the output is often larger than a text PDF. 200 dpi is a good balance for most letters and statements.

Tips and pitfalls

List every form of the information. A name may also appear as initials, a surname alone, an email address or a username. A phone number may be written with or without spaces. Add each version you need gone, separated by commas.

Check every page. The boxes are placed from the PDF's own text positions. Unusual fonts, rotated text and letters spaced apart for justification can shift a box slightly. Look at the download page by page before sharing it, and run it again with a higher resolution or a longer phrase if anything shows.

Scans have no text to search. A scanned page is already a picture, so its words cannot be found. Use the Image Redactor to draw boxes on a picture of the page instead.

The text is no longer searchable. Because every page is an image, nothing in the redacted copy can be selected or searched, including the parts you kept. Keep the original for your own use and share only the redacted copy.

Test what you send. Paste text copied from the downloaded file into the Redaction Checker, or try selecting text in your PDF reader. Nothing should be selectable.

Password-protected files must be unlocked first.

Reading the result

Matches blacked out counts the boxes drawn. Pages with matches shows how many pages had at least one. The preview shows the first page with a redaction. If nothing matched, no file is made and the message suggests why.

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